This PDF file contains the front matter associated with SPIE Proceedings Volume 6783, including the Title Page, Copyright information, Table of Contents, and the Conference Committee listing.

CARRIOCAS project studies and implements in a test bed a very high bit rate (up to 40 Gb/s per wavelength) network tailored for distributed applications. The investigations covers 40Gb/s component, systems and networking; network architecture, protocols and algorithms with a particular focus on application-network cooperation; and remote high resolution collaborative visualisation and distributed storage of massive volumes of data.

For the purpose of reducing the optical networks blocking probability, many wavelength assignment algorithms are introduced to this problem. In this paper, we propose a novel priority-based wavelength assignment algorithm for dynamic traffic in WDM networks. The objective of the algorithm is not only taking the balancing strategy, but also adopting the priority-controlled method. Analytic models and simulations are presented for the proposed wavelength assignment algorithm. By the simulation, we compare the performance of our algorithm with the others under different traffic load and different priority-class. Our algorithm yields better blocking probability performance for different priority requests and the simulation results are also discussed.

The hierarchical multicast routing architecture in intelligent optical networks is investigated in this paper, the two methods of inter-domain information aggregation are given, and two hierarchical multicast routing algorithms are proposed. Their impacts on network performance in terms of blocking probability are evaluated by the simulations in different network models.

IP/WDM traffic grooming is a scheme that let different fine-grained IP layer Packet Label Switched Paths efficiently share the coarse-grained WDM layer lightpath. Choosing those nodes with high nodal degree as the terminals of lightpaths can save the transfer times of Packet LSP, thus on average each lightpath can hold more service to achieve better resource utilization and network throughput. To improve the resource utilization, this paper proposes the Topology-Based Lightpath Establishment Algorithm (TBLEA) which employs network topological characteristics to build more efficient lightpaths whose terminals are with high nodal degree. In the algorithm, a long lightpath, which is potentially less efficient, might be cut into several shorter lightpaths based on the topology characteristics and remaining resource of nodes in the primer lightpath. The algorithm has the advantages that not only the terminal nodes but also the length of new lightpath can promise to improve the PSC and LSC resource utilization. In the implementation of the TBLEA algorithm, a two-layer virtual graph helps to calculate the explicit integrated route to build Packet LSP, and different formulas are adopted to calculate the total costs of existing lightpaths and new lightpaths. A long lightpath might be cut into shorter lightpaths on the basis of the node weight, which is determined by the nodal degree and relative remaining resources. And iterative procedures offer the loop-free optimization of the changed explicit route for Packet LSP.

This paper presents a Sub-domain Initiation Restoration Mechanism which is based on sub-domain restoration of Control Plane and using RSVP-TE as the signaling. When link failure of the control plane happens, traditional control plane restoration, such as the source-initiation mechanism is not efficient enough, because of the long restoration time. Theoretical analyses and results show that the new mechanism can not only reduce the restoration time when compared with source-initiation.

The optical channel pre-emphasis equalization for a 40×40Gbit/s WDM transmission system is experimentally researched in this paper. In our experimental system, three EDFAs are concatenated as booster amplifier. The output spectrum imbalance is 5.0dB, 12.2dB and 7.6dB respectively with input transmitter signal power of 4.5dBm, 0.0dBm and -5.0dBm to EDFA1. For EDFA2 the output spectrum imbalance is 2.3dB, 4.4dB and 7.7dB respectively when input power is 4.5dBm, 0.0dBm and -6.7dBm, and the imbalance is 3.6dB, 5.6dB and 8.6dB for EDFA3 with the same set of input power. The power imbalance of the output spectrum after three spans of 270km changes with the different input power to each EDFA in the system. With the input power to three EDFAs is 5.7dBm, 7.4dBm and 8.0dBm respectively, the output signal spectrum imbalance is about 9.8dB. But with the appropriate input power of 5.2dBm, 3.4dBm and 3.3dBm to three EDFAs respectively, the spectrum imbalance is reduced to 4.3dB. When the input power to three EDFAs are 4.5dBm, 2.2dBm and -3.7dBm, the power imbalance is 9.4dB. The results indicate that, an appropriate choice of input power to three EDFAs, the output signal spectrum after propagation 270km can be equalized to the most extent. With this pre-emphasis equalization, the merit of benefit can be around 5.5dB. Although the equalizer is still necessary, but the requirement for the equalizer is greatly released. The OSNR degradation for the pre-emphasis equalization case is also examined, and about 1.0dB additional degradation is sacrificed. To take into the transmitter signal spectrum imbalance into account, the imbalance of the gain spectrum among 40 channels almost matches that of output signal power spectrum, but the difference is also evident at some channels. Finally, RA pump power is also optimized, and another 1.3dB improvement of channel balance can be achieved.

Using broadband dispersion compensation CFBGs, over 500km-40Gbps NRZ transmission system on G.652 fiber will be demonstrated without electric regenerator, FEC and Raman amplifier. The power penalty is about 2dB @ BER =10^-10.The CFBGs have better performance: 3dB band is about 1.2nm, group delay ripple is less than 25ps near center wavelength, power ripple is less than 2dB, and DGD is less than 1ps. In order to stabilize the DC bias of the LiNbO₃ MZ modulator, a semiconductor cooler is applied to control the temperature. The effect is perfect.

Electronic dispersion compensation is displacing optical compensation at 10Gb/s. How can this be achieved at 40 Gb/s or 100 Gb/s to provide deployable transmission systems with greater capacity?

While today's WDM optical networks are mostly based on 10Gbit/s data, modulated according to the non-return-to-zero format and offer sub-Terabit/s capacities, networks at 40Gbit/s and beyond will likely use more complex modulation formats, possibly involving more than 1 bit/symbol, for compatibility with the 50GHz channel spacing grid. For these formats, two types of detection schemes can be considered: differential detection, or coherent detection. With differential detection, we demonstrated 25.6Tb/s transmission over 240km, using 160 WDM channels on a 50GHz grid, each containing two polarization-multiplexed 85.4Gb/s RZ-DQPSK signals. But coherent detection appears as an even more promising technique for such multilevel formats, to reach higher transmission distances. It provides the real and imaginary parts of the signal, at the expense of larger complexity and cost. These drawbacks should be weighted by the promises offered by the technique when combined with advanced digital signal processing (DSP). DSP not only solves some severe implementation issues, but also holds in store a tremendous potential against fiber impairments. In this paper, we will focus on coherent detection solution and will demonstrate experimentally that a coherent receiver involving DSP can mitigate distortions from chromatic dispersion, polarization-mode-dispersion and narrow optical filtering, even after several thousand kilometers of fiber for 40 and 80Gb/s-modulated channels, thereby paving the way for higher-capacity, longer-reach transparent optical networks, eventually taking advantage of efficient Polarization Division Multiplexing

The unprecedented proliferation of packet-based services such as numerical television, video on demand, is pushing Metropolitan Area Networks (MANs) providers to reconsider their network infrastructures. The existing circuit-based networks are becoming inefficient and costly in supporting the new requirements in terms of quality of service and bandwidth of sporadic packet-based traffic. To solve this problem, new MAN infrastructures are needed. Many propositions of new network solutions were made during the last decade in order to respond to the aforementioned issues, such as Next Generation SONET/SDH, Resilient Packet Ring (RPR). Among others, the optical networking technology appears as a technology of choice for the next generation MANs. The main benefit of optical technology can be resumed in the following terms: huge transmission capacity, high reliability, and high availability. This paper is devoted to provide an overview of the MAN infrastructure, and particularly to its evolution towards optical packet switching (OPS) networks, during the last decades. It also highlights performance issues in optical networking in metro area in terms of optical packet format, medium access control (MAC) protocol and quality of service (QoS), as well as traffic engineering issues. We first begin with a brief state-of-the-art and perspective on optical networking in metropolitan area. Next, we provide the necessary arguments for an answer to the problem of the choice of packet format (fixed format versus variable format) to be adopted in future metropolitan optical packet switching networks. Comparison of different optical packet formats at the electronic to optical (E/O) interface is carried out, followed by the analysis of the impact of optical packet format choices on overall network performance. Then, we explore the performance issue at MAC layer and discuss improvement mechanisms for MAC protocol. Here, fairness and bandwidth utilization issues are specifically investigated. Finally, we discuss about how to guarantee QoS in optical packet switching OPS metro networks, illustrated by a few mechanisms allowing the transport of TDM traffic over packet switching networks (e.g., Circuit Emulation Service - CES).

This paper studies the load balancing strategies in wavelength-routed optical network and a novel load balancing strategy is proposed. The objective of the proposed strategy not only reduces the congestion, but also improves the load distribution state. In addition, the proposed strategy also supports different Classes of Service (CoS). To describe the load distribution state, a variable named the load distribution variance (LDV) is introduced. By reducing the LDV, both congestion and load distribution state will be optimized. Moreover, by dividing the wavelength sets into several separate subsets according to the priorities of connection requests, the strategy can also support different classes of service. Finally, in the network simulation part, the shortest path algorithm with and without adopting the proposed strategy are compared and the numerical results show both the congestion and load distribution state improve by adopting the novel load balancing strategy we reported in this paper.

Based on the layered-graph, this paper proposed an integrated routing algorithm named CIR (i.e., Cost-based Integrated Routing) for IP/GMPLS over WDM networks. Assuming a peer model in GMPLS-Based optical networks, we take into account the network topology and resource usage information on both IP and WDM layers. Focusing on the problems of bottleneck and bandwidth fragment, we combine a cost function of lightpath in our algorithm as the main implement to solve them. The optimized routing scheme is determined by the minimum cost value. In the simulation, we compare CIR with two representative routing algorithms (i.e., HIRA [2] and MinLP [3]) in IP over WDM networks in terms of blocking probability (BP) and wavelength utilization. The result shows that CIR can optimize the network resource utilization to accept more connection requests and reduce traffic BP efficiently.

Grid computing enables the sharing of a wide range of geographically distributed resources including computers, storage systems, specialized devices, and network infrastructures that are owned and managed by different organizations for solving large scale computational and data intensive applications. Optical transports allow a more efficient design by providing the means to transmit large amounts of data with low cost and reliability. Group multicasting is considerable communication requirement in grid networks. Routing and wavelength assignment algorithm can greatly influence the performance of optical network, such as network blocking, resource utilization. This paper investigates the problem of routing and wavelength assignment for group multicast in optical grid networks based on network resource reservation. A minimum resource fragmentation summation (MRFS) algorithm is proposed, presented and evaluated. Simulation results show that the proposed algorithm represents higher performance on reducing blocking probability and increasing resource utilization.

The path-protection scheme in WDM optical networks is addressed, and also the conception of the SRLG (Shared Risk Link Group) is introduced. A new link protection method is proposed, i.e. unrelated SRLG-based Shared-path protection (uSS). The concept of the spare-path set and wavelength-levels cited, the complexity of the algorism is analyzed. The simulations results show that the developed iSS performs well in terms of protection efficiency and the viability of the whole networks , while resource utilized ratio is improved enormously by contraries the possibility of invalidation of both the work-path and the protection-path.

We have demonstrated error-free operations of slow-light via stimulated Brillouin scattering (SBS) in optical fiber for 10-Gb/s signals with different modulation formats, including non-return-to-zero (NRZ), phase-shaped binary transmission (PSBT) and differential phase-shift-keying (DPSK). By directly modulating the pump laser diode (LD) using current noise source, the SBS gain bandwidth and profile can be simply controlled by the peak-to-peak value and power density distribution of the current noise. Super-Gaussian noise modulation of the Brillouin pump LD allows a flat-top and sharp-edge SBS gain spectrum, which can reduce slow-light induced distortion in case of 10-Gb/s NRZ and PSBT signals. For the 10-Gb/s NRZ signal, the error-free slow-light operation has been achieved for the fist time and the corresponding maximal delay-time with error-free operation is 35 ps. Then we propose the PSBT format to minimize distortions resulting from SBS filtering effect and dispersion accompanied with slow light owing to its high spectral efficiency and strong dispersion tolerance. The maximal delay of 51 ps with error-free operation has been achieved. Furthermore, the DPSK format is directly demodulated through a Gaussian-shaped SBS gain, which is achieved using Gaussian-noise modulation of the Brillouin pump. The maximal error-free time delay after demodulation of a 10-Gb/s DPSK signal is as high as 81.5 ps, which is the best demonstrated result for 10-Gb/s slow-light.

We study the transmission performance of Manchester encoded signals over multimode fibers at 1.25 Gb/s and 2.5 Gb/s focusing on regimes where there is strong slowly time varying signal fading and noise corruption. This fading and noise is due both to the modal noise and the dispersion varying cruel environmental effects. A non-return-to-zero (NRZ) modulation scheme typically used in the transmission suffers severally from such slowly varying signal fading; whereas Manchester encoded signal, which carries the binary value by the pulse position within a bit slot, in contrast, has a better performance in coping with the slowly varying signal degradation. In this paper, we study the transmission performance of these two signaling schemes, and the results show that Manchester encoding outperforms NRZ in coping with slowly varying signal degradation.

All-optical label switching (AOLS) is a promising approach of implementing label switching for packet routing and forwarding in the optical layer at high speeds close to fiber line-rates. In this paper, AOLS node architectures with unicast and two multicast approaches are presented. The multicast approaches are referred to as feedback and feed-forward multicast, respectively. We compare these node architectures and evaluate their traffic performance in both unicast and multicast cases with different contention resolution schemes. Simulation results on AOLS nodes of the same dimension are analyzed in terms of packet loss ratio and network throughput.

Nonlinear equalizers based on nonlinear Volterra theory and maximum-likelihood sequence estimators (MLSE) are investigated to mitigate the nonlinear distortions resulting from the incomplete sideband suppression in optical single side band modulation (OSSB) systems. Through theoretical analysis and simulations, we demonstrate that electrical dispersion compensation (EDC) by using these nonlinear equalizers can achieve better performance compared to conventional analog equalizers including feedforward equalizers (FFE) and decision feedback equalizers (DFE).

In this article optical minimum-shift keying (MSK) modulation format in 9×40 Gbit/s wavelength-division multiplexing (WDM) spacing of 100 GHz transmission systems is investigated and compared with return-to-zero differential phase-shift keying (RZ-DPSK) and return-to-zero (RZ). The performance of optical MSK in presence of amplification noise, chromatic dispersion and nonlinear effects is analytically determined. Operations over a wide range of parameters, such as span input power, precompensation value, and chromatic dispersion parameter are performed; experimental results show that optical MSK demonstrates special performance in transmission distance, nonlinear effects, and dispersion tolerance.

In this paper, WDM transmission experiments are discussed showing simultaneous compensation of nonlinear effects and chromatic dispersion through optical phase conjugation (OPC). The performance of OPC and DCF for chromatic dispersion compensation are compared in a wavelength division multiplexed (WDM) transmission link with 50-GHz spaced 42.8-Gb/s RZ-DQPSK modulated channels. The feasible transmission distance for a Q-factor ~10 dB is limited to approximately 5,000 km and 3,000 km for the OPC and the DCF based configuration, respectively. When the Q-factor as a function of the transmission distance is observed, at shorter distances, the Q-factor of the OPC based configuration is about 1.5 dB higher than that of the DCF based transmission system. Up to 2,500-km transmission a linear decrease in Q is observed for both configurations. After 2,500-km transmission, the Q-factor of the DCF based configuration deviates from the linear decrease whereas the OPC based performance is virtually unaffected.

Self-similar pulse propagation properties in Yb⁺³-doped fiber amplifiers with the effects of higher-order dispersion and gain dispersion have been studied in this paper. The effects of initial pulse energy, third-order dispersion and the doped ions dipole relaxation time on the pulse propagation quality are relatively expounded with the analytical and simulative methods. It is shown that with nonlinear area of parabolic pulses being enlarged, the center of chirp moves forward or backward, due to the difference of third-order dispersion coefficient. And the figure of pulses is distorted with the pulse peak delaying to one side and the center location excursing. Gain dispersion can be a filter, which can properly compress pulse-width. Results proved the possibility of the self-similar pulse existing in gain medium with a certain relaxation time.

A simple theoretical model is proposed for the study of timing jitter induced by intrachannel corss-phase modulation (IXPM) in chirped fiber grating (CFG) compensating systems. The mechanism how CFG reduces the timing jitter is studied in detail, theoretically and numerically. The reason why symmetrical power and dispersion scheme could guarantee zero timing jitter is analyzed.

By temporally and spectrally reshaping the gain spectrum of the SOA, we investigate the effect of the backward injecting linewidth on the rise/fall time, duty-cycle and frequency chirp of the 10 Gbit/s format-converted pulsed RZ data-stream from the inverse-optical-comb injected SOA. The NRZ-to-RZ conversion in the SOA under intense XGM not only results in patterning but also induces large chirp with its level proportional to the amount of gain depletion. The multi-wavelength inverse-optical-comb injection effectively depletes the TWSOA gain spectrally and temporally, remaining a narrow gain-window and a reduced spectral linewidth and provide a converted RZ data with a smaller peak-to-peak frequency chirp of 6.7 GHz. The converted pulsed RZ signal is subject to the net effect of addition chirp as well as dispersion being to increase the power penalty of the link. Under the injection of multi- and single-wavelength inverse-optical-comb with average power of 16.5 dBm and duty-cycle of 64%, the peak-to-peak chirp of the converted pulsed RZ signal are 11.95 GHz and 13.23 GHz, respectively. The FWHM of the multi- and single-wavelength injection converted pulsed RZ data are 31.64 ps and 30.81 ps, respectively. The rising time remain almost unchanged, however, the falling time was monotonically reduced by increasing injection power. The evolution of FWHM with injection power exhibits similar trend with falling time. In comparison with single-wavelength inverse-optical-comb injection, multi-wavelength injection exhibits better frequency-chirp reduction performance.

Effect of the initial chirp on picosecond pulse breakup in the presence of noise is analyzed through numerically solving the modified nonlinear Schrödinger equation, using the standard split-step Fourier method. It is found that, for shorter pulses, the pulse breakup is caused by pulse collapse resulted from high-order soliton compression, even in the presence of noise. For longer pulse, pulse breakup is triggered by nonlinear amplification of noise caused by modulation instability. The effect of initial chirp on pulse breakup is closely related to the mechanism of pulse breakup, and the process of short pulse breakup depends strongly on the strength of negative initial chirp.

Passive Optical Network (PON) based access architecture is the most favored choice for delivery of triple-play services today. This paper reviews various PON technologies, requirements, challenges and trade-offs involved in modeling and design optimizations of PON systems and sub-systems, mainly from the physical layer perspective.

Optical burst switching (OBS) is proposed as a high-speed, flexible, and transparent technology. It is thought to be the best way to adapt the bursty IP traffic over optical wavelength division multiplexing (WDM) networks. OBS technology facilitates the efficient integration of both IP and WDM. It provides statistical multiplexing gains and avoids long end to end setup time of traditional virtual circuit configuration. However, there are still a lot of challenges, one of which is burst contention. Owing to the fact that random access memory like buffering is not available in the optical domain at present, there exists a real possibility that bursts may contend with one another at a switching node. Many contention resolutions are proposed. The major contention resolutions in literature are wavelength conversion, fiber delay lines, and deflecting routing. In this paper, a new data burst scheduling scheme, called group scheduling based on control-packet batch processing (GSCBP) was proposed to reduce burst contention. Like transmission control protocol, GSCBP has a batch processing window. Control packets which located in the batch processing window are batch processed. A heuristic scheduling algorithm arranges the relevant bursts' route based on the processing result and the network resource. A new node architecture supporting group scheduling was presented. The GSCBP algorithm is combined with wavelength converter and/or fiber delay lines which is shared by some data channels. Meanwhile, an extended open shortest path first (E-OSPF) routing strategy was proposed for OBS. Both GSCBP and E-OSPF are introduced into 14-node national science foundation network by means of simulations. The ETE delay, burst blocking probability, as well as burst dropping probability were attained. Results show that the GSBCP lead to the higher-priority traffic drop rate decrease one order of magnitude, if drop rate and ETE delay of lower priority traffic is sacrificed.

The proportional differentiated model is very convenient for network operators to quantitatively adjust the quality differentiation among service classes. And optical burst switching (OBS) is considered as the promising switching paradigm of optical internet. So it is very important for OBS to support the proportional differentiated model. A preemption scheme based on batch-scheduling is proposed to provide proportional differential QoS for OBS networks in the paper. The expected burst dropping probability equation of every service class is deduced from the proportional differentiated model. When a batch burst control packets and their corresponding bursts are completely scheduled by LAUC with burst arrival order and some bursts are scheduled unsuccessfully, the preemption scheme is triggered to keep proportional burst dropping probability among service classes according to the expected burst dropping probability equations. The proposed scheme adopts the batch scheduling based on LAUC and burst arrival scheduling order to decrease burst dropping probability. And it adopts the preemption scheme to keep proportional burst dropping probability among service classes. Simulation results show that the proposed scheme can provide proportional differential QoS and efficiently decrease the burst dropping probability.

In an asynchronous optical packet switching network, contention occurs at a node whenever two or more packets are trying to leave the node from the same output port on the same wavelength. As a means of contention resolution, fiber delay lines (FDLs) are commonly implemented in optical buffers. This paper presents an analytic model to study single-wavelength FDL buffer systems with finite waiting places. Considering the delay quantization in FDLs the deference between waiting time and delay time is discussed detailedly and then the packet lengths are modified. Analytic results of the queuing performance can be figured out for the finite FDL buffer system. Accuracy of the proposed model is finally validated through numerical simulation.

In OBS network, one key factor is implementing a switching fabric to achieve low bursts loss rate as low as possible. Another key factor in OBS network is scheduling bursts after switch fabric to an output port to achieve best utilizing bandwidth. Until now the performance of switch fabric and scheduling algorithm is analyzed with a uniform assigned traffic so called in this paper. The uniform assigned traffic is meant that the input traffic go to every output port with a same probability of 1/N independently. Unfortunately, this uniform assigned traffic may not the most suitable way to present the real world traffic. To deal with this problem, we present a new bursty assigned traffic model for analysis and performance evaluation of OBS network. Like a legacy bursty traffic the bursty assigned traffic is divided to two cycle: bursty cycle and nonbursty cycle. The input traffic is directed to an output port with a probability larger than 1/N in bursty cycle and is directed to an output port with a probability less than 1/N or none in nonbursty cycle. Then making use of the definition the bursts loss ratio of switch fabric and the LAUC-VF scheduling algorithm under uniform assigned and bursty assigned traffic is presented and compared in the paper.

We numerically study a novel scheme of chaotic communication based on delayed optoelectronic feedback semiconductor laser with two time delays. By switching the route of optoelectronic feedback between two time delays according to the message, we can generate a chaotic waveform simultaneously with the message buried inside. With the advantage of generating the chaotic carrier while encoding message, the transmission can be much easier and more secure than conventional chaotic communication systems. The chaotic channel message, decoded message, and filtered message for a message bit-rate of 500 Mbits/s that has a Q-factor value of 9.45 are shown. We also study the Q-factor of the filtered message and the channel message after filtering for different message bit-rates. The result shows that this novel scheme can achieve communication with high bit rate and pertain desirable security.

We present a compact short pulses source, in which the pulses generated by large-signal directly modulated laser diode are phase-modulated, and it can compress the pulse from 30ps to 5.3ps with 184fs timing jitter.

An optical secure communication system based on digital chaos and Polarization Shift Keying (PolSK) technology is proposed. In several selected PolSK schemes, states of polarization are partially or totally uniform on Poincare sphere. Different PolSK schemes are chosen according to the real-time chaos-based pseudo-random sequences to modulate original information in different periods of clock of the transmitter. In the receiver, according to the synchronous chaotic sequences, corresponding PolSK schemes are used to demodulate the information. Simulation is carried out by using the softwares of OptiSystem and Matlab. Some analysis results are presented. In the conclusion, this system works well in communication and has strong anti-attack capacity.

40-Gbit/s optical code-division multiplexing (OCDM)/ wavelength-division multiplexing (WDM) system based on supercontinuum (SC) and superstructured fiber Bragg grating (SSFBG) is experimentally demonstrated, simultaneous multi-wavelength optical encoding of a single supercontinuum source using SSFBG is achieved. In the receiver, a nonlinear amplifying loop mirror (NALM) is introduced to improve the system performance, both the sidelobe and the pedestal are reduced, the waveform quality of decoded signal is enhanced. The peak power of the decoded signal before the NALM is ~ 8 mW.

Orthogonal ASK/DPSK labeling is a promising approach to ultra-high packet-rate routing and forwarding in the optical layer. However, the limitation on the payload extinction ratio (ER) is a detrimental effect for the network scalability and transparency. In this paper, we propose and experimentally demonstrate that mark insertion coding is an efficient technique to improve the ER tolerance in optical orthogonal ASK/DPSK labeling scheme using an ASK payload and a DPSK label. The experimental results show that by applying mark insertion coding to an orthogonally labelled signal with an ASK payload up to 40 Gb/s and a 622 Mb/s or 2.5 Gb/s DPSK label, the tolerable payload extinction ratio can be greatly increased up to 13 dB.

In this paper, both numerical and simulated modeling techniques were applied to analyze the influence on the performance of the token-based Optical Burst Transport (OBT) ring networks caused by the parameters, such as the minimum and maximum burst length, the circumference of the ring, and so on. We first analyze the issue by numerical analysis in the case that each node has only one token. After that, we confirm the analytical results and made further researches in the case that each node has multiple tokens by simulated analysis. All the results show that to design a high-performance token-based OBT ring network, not only the common parameters, such as the number of nodes and wavelengths, and the circumference of the ring, but also the special parameters, such as the minimum and maximum burst length, and the offset time should be taken into account. Furthermore, a testbed of Three-node Token-based OBT ring network Using Fixed Transmitter and Tuneable Receiver (FTTR) is constructed. With it, the variations of the network performance caused by the maximum burst length are investigated.¹

On account of the glary future of Optical Burst Switching (OBS) network and the abundant Transmission Control Protocol (TCP) traffic, study of TCP combing OBS are prevail in the recent years. In this paper, we address the issue of assembly algorithm in OBS network based on unsymmetrical TCP traffic. The Optimal Maximum Assembly Length (OMAL) in Max-Time-Min-Max-Length Assembly Algorithm is studied in this paper and an assembly algorithm with edge node differentiation based on unsymmetrical traffic is presented by investigating the feature of TCP flow. We also propose client's Average Download Rate (ADR) as an evaluation standard and the simulation results show that the Assembly Algorithm with EN Differentiation will improve client's ADR a lot.

Optical burst switching (OBS) is thought to be the best way to adapt the bursty IP traffic over optical wavelength division multiplexing (WDM) networks. OBS technology facilitates the efficient integration of both IP and WDM, and it provides statistical multiplexing gains and avoids long end to end setup time of traditional virtual circuit configuration. However, burst contention is inescapable in OBS for connectionless transmission and the absence of optical random-access memory. So many contention resolution methods are proposed. In this paper, a novel decrease contention scheme--IP calking was proposed for optical burst switched networks. IP calking method uses IP packets to carry single-hop traffic and the burst to carry multihop traffic as well, filling gaps between bursts by stuffing IP packets between adjacent nodes. A statistical analysis model was developed to analyze the performance of this method. In an arbitrary network, the analyses indicate that the decrease of packet dropping probability is directly proportional to the link number and almost inversely proportional to the square of the node number. The theoretical results are validated through extensive simulations. Simulation results show that IP calking decreases about 50 % data drop probability of the no calking scheme and the link utilization is improved 5~25% which varying with the offered load in a simple network.

We propose and experimentally demonstrate a prototype 160-Gbit/s/port optical packet switch with narrow-band alloptical code-label processing, optical switching, high-extinction-ratio optical buffering, electrical scheduling, and optical MUX/DEMUX. As related technologies, we also propose and demonstrate a novel system for measuring variable-length packet BER and loss and a burst-mode optical packet 3R receiver.

In this paper, we focus on burst routing strategies and performances in the all optical slotted network investigated by the ROMéO French RNRT project. When routing a burst with a deflection routing strategy the burst (i.e., a sequence of slots to be routed contiguously) can be cut when it is inserted in the network or when the deflection routing decision is not the same for all its slots. We first evaluate the performances of a simple shortest path routing strategy for bursts considering different traffic loads. Then, we propose and compare different routing strategies proposed in the ROMéO project in terms of burst integrity, delay and jitter.

Due to the network resources conflicting, optical burst switching (OBS) network would raise some contentions, which is often resolved by head-drop schemes since they are more simple and intuitional. However, the existing head-drop schemes have two inherent defects, i.e., pseudo-contention and excessive-drop. Besides, they seldom consider how to support QoS. In consequence of the shortcomings, this paper proposed the QoS-aware head-drop scheme, which can selectively discard the head part of contending burst or the entire burst according to the priority and the truncated burst relative length, i.e., the ratio to the original burst length. The simulation results show that it is able to overcome the mentioned shortcomings, and to provide QoS guarantee.

We proposed a novel drop policy in the core nodes which is combined with the determinant strategy in the ingress edge nodes. The proposed drop policy is based on the field of Hop Number (HN) taken by the burst control packets, which is introduced to determine which burst should be dropped when the contention happened in the core nodes. In the drop policy, the long-hop traffic is given the high priority, and most of the retransmitted traffic is left to be short-hop traffic. Therefore, there is a trade-off between the short-hop traffic and the long-hop traffic. The determinant strategy in the edge nodes is an initialized threshold, Retransmission Number Threshold (RNT), which is introduced to determine whether to start a retransmission operation when NAK is received. The unnecessary retransmissions in the network are limited, and the burst loss rate is reduced. The mechanism also takes the upper layer, TCP layer, into account. When the network has already been in the state of real congestion, the retransmission will only deteriorate the network performance. In the case, the combined mechanism leaves the retransmission process to the TCP layer. It can improve the network performance cost-effectively.

This paper introduces a kind of Adaptive Optical Label Packet Switching (AOLPS) technology. Based on Optical Packet Switching (OPS), AOLPS uses optical label to achieve self-routing, and the size of optical packet is self-adaptive. At the edge nodes, IP packets are fist classified into different first-in-fist-out memories (FIFOs) according to their priority levels and destinations, and then being encapsulated into optical packets. The traffic at each FIFO is real-time monitored, and the controller in edge node employs an optimal strategy to generate suitable sized packets for transmission. Large sized packets will be adopted when traffic is heavy, and small sized packets will be used when traffic is light. This self-adaptive switching granularity can greatly improve the network performance.

We demonstrate an optical burst switched network test-bed with three nodes in ring topology. A fixed burst-length assembly algorithm is adopted in data assembly schedule. Through simulation and experimental analysis, this algorithm is testified and the optimized assembly burst length is found at 1024 Bytes.

OBS is a promising network infrastructure. RBUDP is a UDP-based protocol used for large bulk data transfer. Existing research focuses on its performance over long fat networks. In this paper, RBUDP transmission performance over OBS networks is evaluated by simulation and experiment. Experiments show transmission of RBUDP features high (95%) average utilization efficiency of bandwidth and insensitivity to large assembly delay (100ms) and high burst loss probability (1%).

Recently, optical burst switching (OBS), which represents a balance between circuit and packet switching, has opened up some exciting new dimensions in optical networking. Burstification is an important process in OBS networks. Due to the burstification, there are two opposite effects on TCP throughput in OBS networks: delay penalty and amplification effects. In this paper these two effects are experimentally investigated simultaneously for the first time based on an OBS mesh network testbed and some valuable experimental results are achieved. Experimental results show that when BTT is less than 1.5ms, and BLT is in the BLT window, the positive effect on TCP throughput is dominant. On the other hand, if BTT is larger than 1.5ms, the BLT window will be closed, thus the delay penalty will become the dominant effect in the OBS networks.

We have experimentally demonstrated how to generate, transmission and switching 100Gbit/s packet signals. The performance of transmission, switching, and label erasure has also been evaluated.

We propose a routing and wavelength assignment algorithm for Optical Burst Switching (OBS) networks that utilizes centralized control. First, a method that can estimate the expected total blocking time in the network is presented. Then the proposed algorithm minimizes the estimated blocking time by simple iterative local optimization in terms of the traffic demand between each pair of nodes. We demonstrate that the proposed algorithm attains much smaller blocking probability than conventional distributed control algorithms. It is also shown that with introduction of optical buffers and burst retransmission, the proposed method realizes low burst loss rates (<10^-6) acceptable for most applications.

Dynamic Assembly Period (DAP) is a novel assembly algorithm, which is based on the dynamic TCP window. The assembly algorithm can track the variation of the current TCP window aroused by the burst loss events, and update the assembly period dynamically for the next assembly. The analytical model provides the theoretical foundation for the proposed assembly algorithm. Nowadays, there are several kinds of TCP flavors proposed to enhance the performance of TCP, such as Default, Tahoe, Reno, New Reno, SACK, etc., which are adopted in the current internet. In this paper, we evaluated the performance of DAP under the different TCP flavors. The simulation results show that the performance of DAP under Default TCP flavor is the best. The difference in the performance of DAP under such flavors is correlated with the inside mechanism of the flavors. We also compared the performance of DAP and FAP under the same TCP flavor. It indicates that the performance of DAP is better than that of FAP in a wide range of burst loss rate.

In this paper, we present an analytical model to study the performance of unequal probability outputting issue in optical burst switching network. In our model, we give a method to evaluate the blocking probability for multi-class traffic at core router when they choose output ports depending on unequal probability.

A model for a reduced complexity nonlinear electrical equalizer based on the Volterra theory is presented which can be utilized to mitigate dispersion and other distortions in optical communication systems. In recent years several electronic equalizers like the feed forward equalizer (FFE), the decision feedback equalizer (DFE) and the maximum likelihood sequence estimator (MLSE) were intensively investigated in optical communication systems. Also, nonlinear FFE/DFE structures based on the Volterra theory were proposed. These nonlinear equalizers can mitigate the effects of dispersion much better than the classical FFE/DFE but are more complicated to build. In a practical system the Volterra nonlinearity is therefore limited to second and third order. However, the number of filter coefficients for such a nonlinear FFE of appropriate order (e.g. 5 taps) is still very high for the nonlinear parts. This results in a very high effort in the equalizer control and optimization algorithm and makes a practical implementation questionable. In this Paper we present a reduced model for Volterra based nonlinear equalizers were the order of the nonlinear parts can be set separately from the linear order. This results in less complex filter structures as the number of coefficients is reduced drastically.

We established the DPSK generating and receiving system, and realized the different kind of DPSK formats. Then we demonstrated the experiment of automatic PMD compensation in 10Gb/s NRZ-DPSK, RZ33-DPSK, RZ50-DPSK, and RZ67-DPSK systems. Using the particle swarm optimization algorithm in these DPSK systems, the optical signals were successfully recovered instantly from PMD induced distortion after compensation.

PMD vectors can be described by Stokes vectors pointing to the direction of slow PSP with a length equal to DGD. Measuring DOP is a way of obtaining DGD information and the direction of PSP can be characterized by scrambling at the transmitter. When totally polarized optical signals (DOP=1) transmit a distance, DOP decreases due to the influence of PMD. However, if the input SOP is aligned to the direction of the PSP, DOP of optical signals remains unchanged. Placing a scrambler at the transmitter, SOP of input signals covers Poincare sphere at a certain frequency. The effect of PMD on SOPs in different directions changes with transmission, and the output DOP is described and shown. SOPs of two extreme points in the main axis are just two PSPs. After one time scrambling, 3500 SOPs are distributed equally in the Poincare sphere. The DOP of all SOPs can be calculated under the condition that splitting ratio is 0.5, with two SOPs at maximum DOP being two PSPs and two SOPs at minimum DOP being the SOP. Since the whole information of first-order PMD vector can be acquired, feed-forward PMD compensation will be feasible and fast.

A novel scheme of global adaptive dispersion compensation combined with extended control plane in transparent optical networks is proposed. The performance of transport plane of ASON is monitored by extended control plane in this paper. When the residual dispersion at optical receiver can't satisfy the transmission performance demand, a module of compensation budget computing will be activated to compute adjustment quantity of all tunable dispersion compensators, and then every tunable dispersion compensator adjust their parameters respectively according to the adjustment quantity to realize global adaptive dispersion compensation. Simulation results indicate that it is more efficient than separate compensation of using adaptive dispersion compensator.

A modular photonic interconnection network based on a combination of basic 2×2 all-optical nodes where a photonic combinatorial network manages the packet contention, is presented. The proposed architecture is synchronous, can operate Optical Time Division Multiplexing (OTDM) packets up to 160Gb/s and exhibits self-routing capability and very low switching latency. In such a scenario, OTDM has to be preferred to Wavelength Division Multiplexing (WDM), because in the former case the instantaneous packet power carries the information related to only one bit, making more simpler the signal processing based on instantaneous nonlinear interactions between packets and control signals. Moreover OTDM can be utilized in interconnection networks without caring about the propagation impairments, since these networks are characterized by a very limited size (< 100m). Finally, in such a limited domain, the packet synchronization can be solved at the network boundary in the electronic domain, without the need of complex optical synchronizers. The 2×2 switching element is optically managed by exploiting a photonic combinatorial network able to carry out contention detection, and to drive the contention resolution and the switching controller blocks. The implementation of such photonic combinatorial network is based on semiconductor devices, making the solution very promising in terms of compactness, stability, and power consumption. The network performances have been investigated for bit streams at 10 Gb/s in terms of Bit Error Rate (BER) and Contrast Ratio. Moreover, the suitability of the 2×2 photonic node architecture exploiting the above mentioned combinatorial network, has been verified up to 160 Gb/s, demonstrating the potentialities of photonic digital processing in the next generation broad-band and flexible interconnection networks.

Optical switches are key components for applications in 1.31/1.55 µm optical communications, networks and microsystems. They can reduce the cost of the network and increase fiber transmission capacity and at the same time, distribute optical signals to different subscribers. Optical switches in Si-based waveguides make use of changes in the refractive index induced by carrier injection and offer advantages of small device size, polarization independence and capability of integrating with other Si-based optoelectronic devices. By adding Ge into Si, the bandgap of SiGe shifts towards the optical communication wavelength while the refractive index increases, which is good for wave guiding. P-N junction can also be formed easily during SiGe epitaxy. In this paper, six switching approaches at the optical communication wavelength will be introduced.

Hybrid optical switching (HOS) combines the advantages of optical circuit switching (OCS) and optical burst switching (OBS). But HOS can not dynamically change the optical switching paradigm according to the traffic fluctuation. it can not efficiently support burst traffic. And the utilization of some lightpath in HOS networks is low. To solve the problems, a self-adaptive hybrid optical switching (S-HOS) is proposed in the paper. In S-HOS networks, ingress edge nodes monitor the traffic between a pair of an ingress node and an egress node, and based on the monitor results edge nodes self-adaptively adjust optical switching paradigm. Based on minimum burst length maximum assembly period algorithm, a new assembly algorithm of S-HOS is proposed to improve the lightpath utilization and efficiently support burst IP traffic. And a data channel scheduling is proposed to assign data channel resources for the lightpaths and data bursts by regarding lightpath as a huge data burst. And it can decrease the complexity of hybrid optical switching and improve the network performance. Simulation results show that S-HOS outperforms OBS in term of IP packet dropping probability and end-to-end delay.

The semiconductor ring laser (SRL) is attracting more and more interest as a potential all-optical logic device. Whilst previous operations used electrical modulation to induce switching, for all-optical applications such as all optical switching, regeneration, and optical memory it is necessary to switch using an external optical signal. When operated as a monostable way at 110 mA (just above the threshold of 80 mA) where the device operates in the bidirectional regime, SRL should also be dynamically forced to work in clockwise (CW) and anticlockwise (CCW) directions depending on the external injection direction. In this paper the response characteristics of SRL to external optical injection which fed into SRL by CCW direction are investigated. Both output directions have highly nonlinear relationship with injection signal power and their responses are highly digital. This operation is also simulated in both directions and the agreement with experiment is very good apart from the injection power scale. This confirms that the SRL power is constant above a certain injection power level in both on and off directions, which can be further verified by future devices with 2 couplers.

We review the mode-field matched center-launching technique recently proposed for the use in the multimode fiber (MMF) transmission systems operating at the speed higher than 10 Gb/s. This technique has been used for the transmission of 100-Gb/s signal (10 × 10 Gb/s) over 12.2 km of MMF. The performance of this system is surprisingly stable, and not sensitive to the use of fiber connectors in the MMF links.

We investigate the performance of two different all-optical wavelength conversion configurations: four-wave mixing in highly nonlinear fiber and cascaded second harmonic and difference frequency generation in periodically poled Lithium Niobate. Both configurations have the capability to convert phase-modulated signals with high data rates. Error free wavelength conversion of up to 160 Gbit/s DPSK and 320 Gbit/s DQPSK data signals is demonstrated. The converter using highly non-linear fiber can have advantages in network applications in which cascaded wavelength conversion are requested due to its potentially higher conversion efficiency and OSNR. The Lithium Niobate converter generates no phase distortion by wavelength conversion of phase-modulated signals. This could be useful for applications utilizing PSK formats with 2 bit per symbol or more, like DQPSK or 8-PSK.

We analyse the relationship between linewidth of emission spectra of erbium-doped fibers and electronic correlation. We find the crosstalk from FWM and XPM in erbium-doped telluride fibers is weaker than that in erbium-doped silica fibers.

Nonlinear polarization rotation (NPR) in semiconductor optical amplifiers (SOAs) is initially investigated. The changes of ellipticity angle of the probe light in a counter-propagation scheme are presented on the Poincaré sphere, and agree with the numerical simulations. All-optical wavelength conversions based on NPR in SOAs are realized at a bit rate of 2.5Gbit/s.

All-optical format conversions from return-to-zero (RZ) and carrier suppressed RZ (CS-RZ) to non-return-to-zero (NRZ) are demonstrated with a temperature-controlled all-fiber delay interferometer (DI) and narrow-band filters, at 40 Gb/s. The format conversion processes are analyzed in frequency domain. By properly controlling the DI and the tunable filters, for the RZ input, NRZ signal can be achieved at the carrier wavelength from one of the DI output ports; and for the CS-RZ input, NRZ signals can be achieved at two different wavelengths simultaneously from two output ports of the DI. The operation principle is analyzed with spectra evolution analysis. The power penalties are 1.5 dB and 1.8 dB, for RZ and C-RZ to NRZ conversions, respectively.

Hybrid wavelength division multiplexing/optical code division multiple access (WDM/OCDMA) passive optical network (PON), where asynchronous OCDMA traffic transmits over WDM network, can be one potential candidate for gigabit-symmetric fiber-to-the-home (FTTH) services. In a cost-effective WDM/OCDMA network, a large scale multi-port encoder/decoder can be employed in the central office, and a low cost encoder/decoder will be used in optical network unit (ONU). The WDM/OCDMA system could be one promising solution to the symmetric high capacity access network with high spectral efficiency, cost effective, good flexibility and enhanced security. Asynchronous WDM/OCDMA systems have been experimentally demonstrated using superstructured fiber Bragg gratings (SSFBG) and muti-port OCDMA en/decoders. The total throughput has reached above Tera-bit/s with spectral efficiency of about 0.41. The key enabling techniques include ultra-long SSFBG, multi-port E/D with high power contrast ratio, optical thresholding, differential phase shift keying modulation with balanced detection, forward error correction, and etc. Using multi-level modulation formats to carry multi-bit information with single pulse, the total capacity and spectral efficiency could be further enhanced.

Pulse width variation due to source chirp, chromatic dispersion, chip length of en/decoders and its corresponding impact on electrical power at PIN receiver is analyzed in this paper. The result, which is verified by a 2×2 OCDMA system at 127-chip 320-Gchip/s, shows that broadened pulse width degrades SNR. And system performance is limited by not only code length and pulse width, but also chip length.

Correlation characteristics for phase-coding scheme utilizing superstructured fiber Bragg grating (SSFBG) as encoder/decoder are evaluated. The impact of transmission impairments and the receiver's bandwidth limitation in the coherent OCDMA system is investigated, and the performance improvement by using optical thresholding is also analyzed.

In this paper, we analyze the sensitivity degradation of a system due to various orders of chromatic dispersion. To do this, the power penalty of the uncoded and encoded pulse of a coherent ultrashort light pulse Code Division Multiple Access (CDMA) communication system due to various orders of chromatic dispersions are analyzed. Analysis of uncoded pulse shows that the power penalty is unacceptably high when second order dispersion is not compensated. However we can obtain acceptable level of power penalties while compensating second and third order dispersion. Also, due to the high order of dispersion, the power of encoded pulse decreases as it propagates through the fiber which leads to a better Multiple Access Interference (MAI) than reported in previous papers.

A novel scheme of optical access using OCDMA-PON is investigated to support large number of subscribers. Chaotic sequence is proposed to be the spread spectrum sequence of OCDMA system for the first time. The number and length of chaotic sequences are not restricted like conventional sequences. The performance of chaotic sequences is discussed.

We investigated the property of conversion between phase modulation (PM) and amplitude modulation (AM) in optical fiber transmission link due to chromatic dispersion (CD) for the purpose of clock information generation. As a result, a novel all-optical clock recovery (CR) scheme from 10 Gbps non-return-to-zero differential phase-shift-keying (NRZ-DPSK) signal has been demonstrated experimentally. We introduce a chromatic dispersion induced clock tone from the NRZ-DPSK signal and feed it into a free-running semiconductor optical amplifier (SOA) based fiber ring laser to achieve an injection mode-locking. The generated mode-locked pulse is the corresponding regenerated clock of the original signal. Since no special component is required for NRZ-DPSK demodulation, our proposed method is very promising because of its simple configuration and higher stability. In experiments, 20km standard single mode fiber is employed to accumulate CD and generate PM-AM conversion hence regenerate clock tone of the NRZ-DPSK signal. The recovered clock signal with the extinction ratio over 15 dB and the root-mean-square timing jitter of 720 fs is achieved under 2³¹-1 pseudorandom binary sequence NRZ-DPSK signals measurement. We also demonstrated a similar CR system by using a chirped fiber Bragg grating (CFBG) as the dispersion device. With the same operation principle, it is quite convenient and promising to extend our configuration to implement all-optical CR for NRZ-DPSK signal with data rate up to 40Gbps.

A novel 10Gbit/s all-optical packet clock extractor, which comprises a Fabry-Perot (F-P) filter and a semiconductor optical amplifier (SOA), is proposed in this paper. Low Finesse Fabry-Perot (F-P) filter was used to directly extract the packet clock from the data packet stream, which ensures that the clock locks fast and vanishes quickly. The clock, amplitude modulated as a result of low-Q filter, then goes into SOA to reduce the low-frequency amplitude noise. The impact of F-P filter and SOA on the locking and unlocking time of the packet clock is theoretically analyzed. The result shows that the locking time is reduced while the unlocking time is increased, due to the self-gain modulation (SGM) effect. We demonstrate instantaneous 10.075GHz clock extraction experimentally with the establishing time of about 8 code-periods and vanishing time of about 22 code-periods.

In the present communication we discuss recent advances in the development of Semiconductor optical amplifier (SOA)-based interferometric optical gates and their use through the implementation of functional high-speed optical systems. SOA Mach-Zehnder interferometers (SOA-MZI) show great potential for being used as fundamental building blocks in developing intelligent high speed all-optical sub-systems. In this context we discuss the development of optical systems that perform diverse and non-trivial network functionalities that find application in Optical Packet/Burst Switching networks (OPS/OBS). The use of generic building blocks to develop a variety of optical sub-systems is essential, as this avoids the requirement for custom-made technological solutions and allows for a common fabrication procedure for all subsystems. In this context, we discuss latest research on integration of arrays of such optical switches onto the same photonic chip using hybrid integration technology. The development of such arrays reduces the cost of photonic devices by sharing the packaging and pigtailing costs. By using an integrated quadruple array of SOA-MZI switches we demonstrate the front-end unit of an All-optical Label Switched node that performs clock recovery, data recovery and label/payload separation, and a scalable Time Slot Interchanger (TSI), proving the multi-functionality and processing power of such device. Both functional systems exhibit comparable performance compared to implementations using single switches with significantly lower device costs. The cost reduction offered by the integration of multiple switches on the same chip is also evident in high-speed WDM networks, where multi-wavelength regeneration can be achieved with the use of several integrated switch arrays.

We experimentally demonstrate a 4×10-Gb/s optical multicast scheme using a semiconductor optical amplifier (SOA) and a single optical source, which produce a 10-GHz multi-wavelength pulse-trains used as the probe light of the SOA. The multicast principle is based on the multi-wavelength conversion (MWC) by means of the interaction of both cross gain modulation (XGM) and transient cross phase modulation (T-XPM) of the SOA. Because of the nonlinear amplification of SOA, the 4 output copies are regenerated with respect to the input degraded signal. This scheme is very simple and allows photonic integration.

We demonstrate a simple configuration for clock recovery from nonreturn-to-zero (NRZ) signal, which is preprocessed by a narrow-band filter. Clock component is enhanced evidently after the filter. Compared with previous preprocessing schemes, the single filter is simple and suitable for different bit-rates. The output performances related to the bandwidth and the detuning of the filter are analyzed. By cascading a clock recovery unit with semiconductor optical amplifier based fiber ring laser, clock signal can be extracted from the preprocessed signal with extinction ratio over 10 dB and root mean square timing jitter of 900 fs, at 10 to 40 Gb/s. By simply using a filter with larger bandwidth, much higher bit-rate operation can be achieved easily.

We have experimentally investigated the reflection tolerance of upstream signals by comparing Manchester-encoded downstream signals with NRZ ones in a RSOA-based fiber loop back system for a WDM PON. The results showed that the reflection tolerance of the upstream signals strongly dependeds on the downstream signal modulation formats, and that the Manchester format was more tolerant than the NRZ one against the reflection of the upstream signal.

Tunable OTDR based on self-locked RSOA for in-line monitoring of WDM-PON is proposed and demonstrated. The characteristics of self-locked RSOA were experimentally studied. The tunable OTDR was successfully demonstrated for a range of 25 nm, having a dynamic range of about 15 dB. Under in-service state of 2.5-Gb/s data, the power penalty induced by the line monitoring channel was about 0.1 dB at BER of 10^-9. The proposed tunable OTDR is cost-effective and useful to monitor the status of WDM-PON.

With the development of backbone communication network, EPON will be the main method for broadband access techniques.EPON has 1Gb/s broadcast ability in downstream. This paper researches DDBA (downstream dynamic bandwidth allocation) management and traffic control mechanisms, and brings forward a LLID (end user) based solution. The emulation results show the proposed solution supports high priority delay sensitive service such as TDM E1 perfectly, and also keep the high throughput.

22-channel detuning capacity of a 2.5Gbit/s directly modulated FPLD based ONU under side-mode injection-locking for DWDM-PON is demonstrated with SMSR >35dB, Q-factor 6.8-9.2, locking range of 24nm, power penalty of -0.7dB, and BER of 10^-10 at -17dBm. The demonstrated side-mode injection-locked FPLD is a potential candidate to achieve the cost effective and high capability 2.5Gbit/s DWDM-PON systems. The maximum usable ONU channels of the side-mode injection-locking FPLD are 22, corresponding to a wavelength locking range of 24 nm. Direct modulation of the upstream channels was successfully obtained and shows high quality eye diagram at ONU transmission.

In this paper, we will discuss the utilization of optically injection-locked (OIL) 1.55 μm vertical-cavity surface-emitting lasers (VCSELs) for operation as low-cost, stable, directly modulated, and potentially uncooled transmitters, whereby the injection-locking master source is furnished by modulated downstream signals. Such a transmitter will find useful application in wavelength division multiplexed passive optical networks (WDM-PONs) which is actively being developed to meet the ever-increasing bandwidth demands of end users. Our scheme eliminates the need for external injection locking optical sources, external modulators, and wavelength stabilization circuitry. We show through experiments that the injection-locked VCSEL favors low injection powers and responds only strongly to the carrier but not the modulated data of the downstream signal. Further, we will discuss results from experimental studies performed on the dependence of OIL-VCSELs in bidirectional networks on the degree of Rayleigh backscattered signal and extinction ratio. We show that error-free upstream performance can be achieved when the upstream signal to Rayleigh backscattering ratio is greater than 13.4 dB, and with minimal dependence on the downstream extinction ratio. We will also review a fault monitoring and localization scheme based on a highly-sensitive yet low-cost monitor comprising a low output power broadband source and low bandwidth detectors. The proposed scheme benefits from the high reflectivity top distributed Bragg reflector mirror of the OIL-VCSEL, incurring only a minimal penalty on the upstream transmissions of the existing infrastructure. Such a scheme provides fault monitoring without having to further invest in the upgrade of customer premises.

We evaluate the performance of wavelength-locked Fabry-Pérot laser diode and spectrum-sliced ASE source for a high-speed (beyond 1.25 Gb/s) signal transmission in wavelength-division-multiplexed passive optical networks (WDM PONs). The impacts of relative intensity noise and fiber chromatic dispersion on the system performance are mainly investigated. In addition, we analyze the maximum reach of our proposed long-reach WDM PON architecture which utilize the distributed Raman amplification and pump recycling technique.

Using the ultrashort pulse and such highly nonlinear fibers, we can obtain large nonlinear optical effects effectively. The group of author has been working on the highly functional optical control using ultrafast nonlinear optical effects induced by ultrashort pulse. We have demonstrated 1.55 - 2.0 μm and 1.0 - 1.7 μm widely wavelength tunable ultrashort pulse generation system by use of ultrashort pulse fiber laser and optical fibers. We have also demonstrated 1.0 - 2.0 μm ultrawideband super continuum generation using ultrashort pulse fiber laser and highly nonlinear fibers. Recently, low noise and highly coherent high quality super continuum generation has been demonstrated for the first time. When the optical pulses overlap in the optical fibers, the pulse trapping occurs and they copropagate along the fibers under some conditions. The author has discovered the two novel pulse trapping phenomena. One of them is the pulse trapping across the zero-dispersion wavelength. In this phenomenon, the optical pulse at normal dispersion region is trapped by the ultrashort soliton pulse at anomalous dispersion region. We can tune the wavelength, output time, and temporal shape of trapped pulse. We can also trap the only one pulse in the pulse train selectively using this technique. The other pulse trapping phenomenon is between the orthogonally polarized ultrashort pulses in polarization maintaining fibers. We can also amplify the trapped pulse using this phenomenon. The highly functional ~1 THz ultrafast all optical switching was also demonstrated by use of these techniques.

We experimentally demonstrate optically tunable buffer in a nano-scale silicon microring resonator with a 20-μm radius. The delay-tuning mechanism is based on the red shift of the resonance induced by the thermal nonlinear effect. We use a non-return-to-zero (NRZ) pseudo random bit sequence (PRBS) signal with different data rates as the probe signal, and investigate its delay performance under different pump powers.

The routing decision functionality by all-optically interconnecting semiconductor-based all-optical logic gates and flip-flops is demonstrated in the frame of an all-optical packet switching network. We experimentally show that the output of the all-optical 2-bit correlator is capable of toggling the states of the integrated flip-flop every 2.5 ns via an adaptation stage. High extinction ratios are obtained at the output of the flip-flop, which can be used to feed a high-speed wavelength converter to complete the routing functionality of the AOLS node. The potential integration of these SOA-MZI based devices make the proposed approach a very interesting solution for future packet switched optical networks.

We demonstrate a novel 40-Gb/s all-optical serial to parallel converter (AOSPC), which can convert 40-Gb/s serial optical signals to 4-channel 10-Gb/s parallel optical signals. Moreover, based on the sequential multi-wavelength conversion the AOSPC shows the regeneration ability.

Presented principle of PSW is based on rate-equation model in the SOA. The TE and TM modes experience different refractive indexes, which lead to phase difference between the two modes, then they interfere at the output of the SOA, and the switching effect is obtained. The rate-equation model is effective in describing the switching effect. But in experiments, this model is hard to realise and track on line, and there are many difficulties for achieving the switching effect. In the SOA, there are four nonlinear effects: cross-gain modulation, cross-phase modulation, cross-polarization modulation, and four-wave mixing. These nonlinear effects are widely researched in optical devices. Several models that describe the nonlinear effects had been presented. Moreover, these models are microscopic models that describe the SOA carrier dynamics, and in many experimental setups, SOAs are pigtailed with standard signal mode fibers at input and output. But the changes of polarization state in the pigtail fiber remain unnoticed. In this paper, we present a macroscopic model of SOA that includes pigtailed fiber and SOA. In this model, we use principal states of polarizations (PSP) to analyse the nonlinear polarization rotation. The PSPs are defined as those output SOPs that remain unchanged to the first order approximation, when the parameter, such as bias current or power of optical control pulse, is adjusted. Our model is a more practical design tool for optical switching configuration. We develop a theoretical relationship between the polarization rotation and the bias current of the SOA. Then, the nonlinear polarization switching is demonstrated. Compared with the reported Optical switching that based on rate-equation model, this switching is stable and easier to be realised. In section II, we present the model based on the principal states of polarizations (PSP). Experimental results show that this model can explain the nonlinear polarization rotation in SOA. In section III, we demonstrate the polarization switching use polarization rotation. We find an excellent agreement between our model and experimental results. We conclude our paper by summarizing important finding in section IV.

Although polarization-mode-dispersion (PMD) greatly impairs conventional high-speed single-carrier systems, it is shown that for multi-carrier systems such as coherent optical orthogonal frequency division multiplexed (CO-OFDM) systems, not only does PMD not cause any impairment, but it also provides a benefit of polarization diversity against polarization-dependent-loss (PDL) induced fading and consequently improves the system marginBegin the abstract two lines below author names and addresses. In this paper, we present the model for the optical fiber communication channel in the presence of the polarization effects. It shows that the optical fiber channel model can be treated as a special kind of multiple-input multiple-output (MIMO) model, namely, a two-input two-output (TITO) model which is intrinsically represented by a two-element Jones vector familiar to the optical communications community. The detailed discussions on variations of such coherent optical MIMO-OFDM (CO-MIMO-OFDM) models are presented. Furthermore, we show the first experiment of polarization-diversity detection in CO-OFDM systems. In particular, a CO-OFDM signal at 10.7 Gb/s is successfully recovered after 900 ps differential-group-delay (DGD) and 1000-km transmission through SSMF fiber without optical dispersion compensation. The transmission experiment with higher-order PMD further confirms the resilience of the CO-OFDM signal to PMD in the transmission fiber.

We experimentally demonstrate a directly modulated 1% AR-FPLA based ONU under side-mode injection-locking for 1.25Gbits/s DWDM-PON application. With side-mode injection of this device, the characterizes of 34-channel detuning capacity under self seeding and its corresponding to a wavelength locking range of 30 nm is a potential candidate to achieve the cost effective and high capability 1.25 Gbits/s DWDM-PON systems. The effects of the front-facet reflectivity in the AR-FPLA on injection locking range, spontaneous emission, and Q-factor are interpreted from our results. A BER of <10^-12 is obtained for the nearest 17 channels and a 10^-10 error rate can be achieved for all of the 34 injection-locked channels with SMSR >35dB, providing a negative power penalty of -0.7 dB.

A simple low-cost wavelength-shared WDM-PON (Wavelength-Division Multiplexing Passive Optical Network) system using star-shaped optical fiber couples, one tunable laser, AWG (Array Waveguide Gating) is proposed in this paper. In this simple architecture, a star-shaped optical fiber couple and a tunable laser are used for 32 sources to reduce the cost dramatically. Comparing with the normal OLT(Optical Line Terminal) controlling ONU(Optical Network Unit) software method, a hardware wavelength collision test method to avoid the wavelength collision for upstream channels is used in the novel system which can reduce delay time for upstream channels. Transmission tests show that the system and the method are efficient which are useful in FTTH(Fiber to Home).

With the rapid increase of Ethernet speed, it is of necessity to improve transport performance of Ethernet physical channel. Based on frame structure defined in IEEE Std 802.3, a kind of frame structure comprising forward error correction (FEC) contents is presented. A FEC method based on the frame structure is brought forward. The method includes error correction functions as well as a mechanism to detect the performance of the physical channel and adjust the FEC configuration adaptively in order to decrease the cost brought by the FEC method. An Ethernet interface using the FEC method can interwork with an ordinary non FEC Ethernet interface. Detailed analysis for performance of the FEC method is given too. A kind of network device that realizes the FEC functions is designed and a test topology is set up to test and evaluate the FEC method.

Fiber-radio systems based on directly modulated high-speed VCSELs are investigated at both 850 nm and 1300 nm. Multimode fiber for short reach applications as well as single-mode fiber to bridge longer distances have been demonstrated to show high performance. Laser noise and linearity characterization as well as system design to achieve high spur-free dynamic range of >95 dB•Hz^2/3 are discussed. A comparative study of radio signal transport solutions based on fiber or coaxial cable is presented and the long transmission distances achievable over multimode fiber links presented. A picocellular network demonstrator comprising of 14 cells with a 4 m radius to investigate networking issues was developed and key performance results are presented.

We proposed a new bidirectional gigabit wavelength division multiplexed/radio on fiber (WDM-RoF) system which shares the same wavelength. A central station for downlink transmits a 3GHz wireless signal which is modulated 1.25Gbps by use of a mach-zehnder modulator. A base station for uplink a transmits 1.25Gbps down-converted wireless signal by using a reflective semiconductor optical amplifier. We achieved a BER<10^-9 of the downlink at -18.3dBm and of the uplink at -22dBm after 20km transmission.

In this paper, a novel scheme to generate millimeter-wave with wavelength reuse by using one modulator has been proposed. In such a system, a continuous wave lightwave is intensity-modulated via a dual-arm LiNbO₃ Mach-Zehnder interferometer modulator with DC biased at υ _π and driven by two complementary modulation signals, which are composed of a lower frequency RF cosine signal mixed with baseband signals by an electric mixer and a higher frequency RF cosine signal. The optical carrier is suppressed and the generated optical signal mainly consists of four sidebands, in which only two sidebands carry baseband signals. At the base station, an optical interleaver is used to filter out the proposed optical mm-waves from the sidebands and another IL is used to filter out the wavelength reused for uplink connection from the rest sidebands. The transmission performance of system is analyzed theoretically and numerically.

A novel scheme is proposed to generate a millimeter-wave (MMW) optical pulse by combining optical time division multiplexing (OTDM) technology and temporal Talbot effect (TTE). A n:1 time multiplexer is used for OTDM, and an LCFG plays a role of TTE. The basic principle is analyzed by using a Gaussian input short pulse, and its characteristics are discussed by numerical simulation. It is shown that the proposed scheme is feasible for MMW signal generation and has potential merits for practical application of Radio over Fiber (ROF) technology.

A new optical heterodyning method based on the Fiber Bragg Grating Filters is proposed. Because the two optical waves for heterodyning are filtered from a single laser, this technique can eliminate the phase noise of the usual optical heterodyning technology and the system performance is improved. With the simulation results, the system's transmission performance of the optical millimeter wave by the new method is verified.

It is essential to extend the optical buffer depth to meet the burst-mode packet requirement. In this paper, we propose to incorporate the Mach-Zehnder interferometer (MZI) into our successful SOA-based dual loop optical buffer (DLOB) configuration. The maximum packet length for the DLOB storage is evaluated theoretically, and the fiber loop utilization can be greatly enhanced with our modified configuration. Then we have successfully demonstrated the 2.5 Gbps variable-length packet loadable function with the MZI-DLOB configuration. The waveform of variable-length packet is little degraded after optical storage. Meanwhile an effective polarization stable method is also experimentally implemented to reduce the instability of MZI-DLOB. All the obtained results confirm the feasibility of our configuration to apply in variable-length optical packet switching.

This paper proposes an all-optical label processing scheme using multiple optical orthogonal codes sequences (MOOCS) for optical packet switching (OPS) (MOOCS-OPS) networks, for the first time to the best of our knowledge. In this scheme, the multiple optical orthogonal codes (MOOC) from multiple-groups optical orthogonal codes (MGOOC) are permuted and combined to obtain the MOOCS for the optical labels, which are used to effectively enlarge the capacity of available optical codes for optical labels. The optical label processing (OLP) schemes are reviewed and analyzed, the principles of MOOCS-based optical labels for OPS networks are given, and analyzed, then the MOOCS-OPS topology and the key realization units of the MOOCS-based optical label packets are studied in detail, respectively. The performances of this novel all-optical label processing technology are analyzed, the corresponding simulation is performed. These analysis and results show that the proposed scheme can overcome the lack of available optical orthogonal codes (OOC)-based optical labels due to the limited number of single OOC for optical label with the short code length, and indicate that the MOOCS-OPS scheme is feasible.

A coherent optical en/decoder based on photonic crystal (PhC) for optical code-division-multiple (OCDM)-based optical label (OCDM-OL) optical packets switching (OPS) networks is proposed in this paper. In this scheme, the optical pulse phase and time delay can be flexibly controlled by the photonic crystal phase shifter and delayer using the appropriate design of fabrication. In this design, the combination calculation of the impurity and normal period layers is applied, according to the PhC transmission matrix theorem. The design and theoretical analysis of the PhC-based optical coherent en/decoder is mainly focused. In addition, the performances of the PhC-based optical en/decoders are analyzed in detail. The reflection, the transmission, delay characteristic and the optical spectrum of pulse en/decoded are studied for the waves tuned in the photonic band-gap by the numerical calculation, taking into account 1-Dimension (1D) PhC. Theoretical analysis and numerical results show that optical pulse is achieved to properly phase modulation and time delay by the proposed scheme, optical label based on OCDM is rewrote successfully by new code for OCDM-based OPS (OCDM-OPS), and an over 8.5 dB ration of auto- and cross-correlation is gained, which demonstrates the applicability of true pulse phase modulation in a number of applications.

A displaying technique of real three-dimensional (3D) dynamic images inside a transparent liquid is demonstrated for the first time. Images were formed by micro-flashes generated by means of laser breakdown in liquid. Amongst several types of liquid tested, tap water was found to be an optimal medium for the displaying due to its lowest breakdown threshold power. Electronic color filter was exploited for dynamic coloring of flashes in synchronization with 3D steering of laser beam's focal point.

In order to reducing the blocking probability, many routing and wavelength assignment algorithms are introduced to this problem. It is crucial for the optical networks to utilize the network resources properly. In this paper, a novel adaptive algorithm is presented for routing in WDM networks. The objective of the algorithm is not only considering the distance vector as the routing cost, but also adopting the load balancing strategy. The simulations for the NSFNET show that the blocking probability and the degree of load balance are both improved with our algorithm compared with some formers.

In the paper, The importance of research in non-line-of sight(NLOS) ultraviolet(UV) propagation channel is first pointed out, and then an experimental system based on Lock-In-Amplifier (LIA) technology is set up to explore the NLOS UV propagation channel characteristics in the atmosphere, and the related experimental results are good helpful to design and evaluate the NLOS UV communication system. The research results show that: firstly, the received energy decreases much quickly with the distance enlarged, and it is also influenced by the emitting elevation angle and emitting field of view angle; secondly, the visibility, wind force, rain rate and fog has little influence on the received power in the short working distance, but with the propagation distance is getting longer, the fog play an very important role on the received signal; finally, some effective methods to enlarge UV communication system distance are discussed, such as UV source power, received antenna diameter and UV detector quality, and experimental data show that the best way to improve UV communication system is to improve the detector sensitivity.

Wavelength converter is widely used to resolve packet contention in optical packet switching (OPS). In this paper, fixed wavelength converters (FWCs) are adopted as contention resolution. In order to realize an acceptable packet loss probability, a structure called FWCA (Fixed Wavelength Converters Array) is proposed. The wavelength conversion capacity of an FWCA is the same as that of a tunable wavelength converter, however, its wavelength conversion capacity can be fully utilized. The performances of an optical packet switch with FWCAs and output optical buffers are evaluated by simulation experiments.

All-optical wavelength converters (AOWCs) that utilize nonlinearities in semiconductor optical amplifiers (SOAs) have attracted considerable research interest. AOWCs based on cross gain modulation (XGM) have a large dynamic range of the input optical signal power but a low extinction ratio (ER) and a high chirp, whereas AOWCs based on cross phase modulation (XPM) provide a low chirp and a high ER but suffer from a relative small input power dynamic range. We point out that there seems to be some complementarity between XGM and XPM. Based on this, we propose a novel scheme for cascaded wavelength conversion based on cross gain modulation and cross phase modulation in SOAs thus is expected to have a high ER and a large input power dynamic range simultaneously. The wavelength conversion operation includes two stages, that is, XGM in the first stage followed by the stage of XPM. In the XGM stage, we use a band pass filter to increase the frequency response of the SOA. In the XPM, we use the bidirectional input scheme for MZI to improve the response of XPM and cancel XGM-induced intensity unbalance to get a relative perfect interference.

Model of non-line-of-sight (NLOS) UV transmission was introduced, NLOS UV transmission was simulated using Monte-Carlo method. Impact of visibility, rainfall, wind speed, light source radiation power, detector sensitivity on transmission range was debated. Results showed that visibility and rainfall had relative impact on transmission range, while wind speed hardly had any influence, it was a main way to improve range by enhancing detector sensitivity, and it weren't very effective to increase source radiation power.

OPS with feedback shared FDL buffer produce large voids due to FDL buffers only supplying discrete step delay and causing FDL queue virtually occupation. By analyzing the TCP traffic and ACK packets feature, the ACK packet void filling first scheduling is presented to decrease packet loss rate and to reduce the FDL voids. When the FDL buffer void size is fit for the ACK packet, the ACK packet is scheduled to FDL immediately. An ACK and non-ACK packets difference and process flow is designed according the TCP packet frame structure. Compared with the conventional FIFO scheduling and smallest FDL void first scheduling, the algorithm reduces greatly the number of ACK occupying the FDL buffer and eliminates large numbers of ACK's bad influence on efficiency of IP data transmission under different FDL buffer depth and traffic load. The results of simulation show that the proposed scheduling makes use of ACK packets first void filling scheduling mechanism to reduce FDL excess load, increases output utilization and reduce packet loss ratio for asynchronous optical network. This approach is shown to minimize the FDL numbers with the feature of high stabilization and photonic integration and to improve real time TCP traffic performance for Internet network.

We study the polarization mode dispersion (PMD) compensation performance of different modulation formats. Firstly, we analyze the relationship between the signal's degree of polarization (DOP) and differential group delay (DGD) of different modulation formats. The results show that the differential phase-shift keyed (DPSK) modulation formats are more suitable for PMD compensation system than the ON-OFF keying (OOK) modulation formats because the DOP-DGD curves of DPSK signals are monotonic and it is easy to search the global maximum. Secondly, we study the PMD compensation performance of the mentioned modulation formats with DOP as feedback signal. It is shown that the modulation formats with smaller bandwidth have better PMD compensation performance, and that PMD compensation performance of DPSK formats are better than that of OOK formats. CSRZDPSK combines the carrier-suppressed characteristic of CSRZ format and specific spectrum characteristic of DPSK format, thereby it has the best performance of PMD compensation.

According to the tilted incidence characteristics of thin film narrowband interference filter, the stack of four cavities angle-tuned narrowband filter with low polarization dependent loss is designed. Using this kind fo angle-tuned thin film filter, one new structure of three-port tunable filter is developed. The experimental results show that its tunable range is at about 20nm.

A parallel optical communication subsystem based on a 12 channels parallel optical transmitter module and a 12 channels parallel optical receiver module can be used as a 10Gbps STM-64 or an OC-192 optical transponder. The bit error rate of this parallel optical communication subsystem is about 0 under the test by SDH optical transport tester during three hours and eighteen minutes.

In this paper, a novel load-balance algorithm is proposed to provide an approach to optimized path selection in automatically swiched optical network (ASON). By using this algorithm, improved survivability and low congestion can be achieved. The static nature of current routing algorithms, such as OSPF or IS-IS, has made the situation worse since the traffic is concentrated on the "least-cost" paths which causes the congestion for some links while leaving other links lightly loaded. So, the key is to select suitable paths to balance the network load to optimize network resource utilization and traffic performance. We present a method to provide the capability to control traffic engineering so that the carriers can define their own strategies for optimizations and apply them to path selection for dynamic load balancing. With considering load distribution and topology information, capacity utilization factor is introduced into Dijkstra (shortest path selection) for path selection to achieve balancing traffic over network. Routing simulations have been done over mesh networks to compare the two different algorithms. With the simulation results, a conclusion can be made on the performance of different algorithms.

A configuration of transmitter for superimposing DPSK signals on dark RZ signals with tunable duty cycle was proposed. The transmitter comprises two optical phase modulators and a delayed line Mach-Zehnder interferometer. The simulation results show that the spectral efficiency is doubled by using this scheme.

In this paper, a novel scheme utilizing the dual-pump FWM in SOA is proposed for the frequency up-conversion and the generation of mm-wave. Characterized by its large conversion range, the proposed scheme has the potential to generate mm-wave at much higher frequency and to convert several signal channels simultaneously. Performance of the system is analyzed through a numerical model and the impact of the pumps power on the conversion efficiency is discussed.

Hybrid waveband/wavelength switching in intelligent optical networks is gaining more and more academic attention. It is very challenging to develop efficient algorithms to efficiently use waveband switching capability. In this paper, we propose a novel cross-layer routing algorithm, waveband layered graph routing algorithm (WBLGR), in waveband switching-enabled optical networks. Through extensive simulation WBLGR algorithm can significantly improve the performance in terms of reduced call blocking probability.

Packet scheduling plays an important role in the asynchronous optical switched networks for node performance. A weighted scheduling algorithm based on the queue length associated with waiting delay was proposed to solve the packet starvation of queue length weighted scheduling for the length variable OPS. The contention is resolved either in wavelength domain by limited range wavelength converters and in time domain by fiber delay lines. The work has contributed with a very powerful scheduling mechanism which reduces resource contention at the asynchronous OPS core nodes and guarantees a reasonable packet delay thanks to its weighted scheduling algorithm based on queue length and waiting delay for variable length OPS network. The scheduler calculates every input ports with N×K virtual output queue (VOQ) weight and schedules the maximal weight queue packets to available output channel. The analysis and simulation results show that the proposed scheduling has high throughput and low packet loss ratio.

An optical header extraction structure and scheme based-on SOA and improved M-Z interferometer were presented in the paper. The parameters of improved SOA-M-Z interferometer are discussed and analyzed to optimize the performance of optical header extraction with the proposed scheme. Numerical analysis and simulation show that more than 15dB contrast ratio of the header extraction is achieved when the rates of header and payload are 2.5Gb/s and 40Gb/s respectively. In addition, the system is simple structure, highly scalable and photonic integration.

Dynamics of (1+1)D spatial solitons in photorefractive medium with drift and diffusion nonlinearity is investigated. Propagation of solitons is analyzed theoretically by means of effective-particle approach method. The explicit formula of acceleration of soltion is derived. Analytical results show that the solitons evolve with a constant acceleration along a parabolic trajectory. The acceleration is determined by the input soliton and the diffusion nonlinearity. We also simulate the propagation of solitons numerically and excellent agreements are obtained between the theoretical and numerical results.

It is important to analyse blocking probability in the WDM networks. In this paper, we present an analytical model for supporting multi-class service with the blocking probability analysis and adaptive routing algorithm to solve the potential shortcomings in the real network. We make the use of the idea of segmented routes according to the finite wavelength conversion resources. We then combine the each segment to get the whole blocking probability. The results show that, by adopting the adaptive routing algorithms, the network can calculate the blocking probability for all the candidate routes, and the request which takes the highest priority will choose the minimum blocking probability route. There are two features in our paper. First, a method of segmented route is designed. Second, use k-shortest routing algorithm to get the minimum blocking probability routing between source node and destination node.

In the current DWDM network, one of the critical design issues in the utilization of networks is careful planning to minimize burst dropping resulting from resource contention. The provision of suitable planning before metadata are sent is critical to improve the rate of successful transmission. In this paper, we attempt to adopt a novel data mining approaches to determining a suitable routing path in the OBS network. Instead of using label switching techniques in DWDM, we proposed the hybrid OBS routing planning on the basics of Cloud Association Rules Algorithm, thus reduced the transmission collision rate in OBS routing. This paper searches for the optimal routing path from all the possible routing paths using cloud association rule approach with Apriori-gen algorithm based on the PACNet topology. The heuristic rules discovered by Apriori-gen algorithm are stored in the Knowledge Base (KB) as references for determining the most suitable routing path. The Knowledge Base of the routing path are set up by means of optimal path routing with the highest successful rate which is mined from the database of historical routing paths using cloud association rules. The experiment results show that the successful rates of routing paths obtained by the proposed routing planning approach can effectively improve the successful rates of transmission.

A improved theoretical model for wavelength conversion into which the mutual coupling parameter is introduced is present. The bit error rate of wavelength conversion are analyzed and confirmed by value simulation.

In this paper, we proposed a variable operation of a DC-OFS based on double SFG+DFG (Double-SFG+DFG-OFS) nonlinearity process for the first time. We studied the principle and configuration of three DC-OFS in detail both theoretically and experimentally. In order to compare with Double-DFG-OFS and Double-SHG+DFG-OFS, we also used two four-channel-controlling multiple-quasi-phase-matched LiNbO₃ wavelength converters and got ten different outputs spreading across a wavelength range of as broad as 35 nm by changing the combination of two controlling wavelengths of the two wavelength converters. And one channel signal was converted to shorter and longer wavelength and the same wavelength by changing the controlling wavelengths. We got higher conversion efficiency compared with the other two DC-OFSs mentioned above. We used novel M-QPM-LN wavelength converters having a continuously-phase- modulated domain structure, which can be operated by multiple pump wavelengths with minimum loss of efficiency. The periods were 14.8μm. The phase of the periodic poling was continuously modulated to satisfy the QPM condition at four different wavelengths. The frequency spacing of control signal-b is twice as large as the control signal-a. The operating temperatures were 102.5 and 100.5 C for the first and the second QPM-LN wavelength converters, respectively.

A model for received signals has been developed for detection of binary data bits in the presence of atmospheric turbulence noise. The model was used to analyze the likelihood ratio test (LRT) according to optimal maximum a posterior (MAP) probability criterion. The adaptive decision thresholding method was developed to maintain the detection threshold near optimum. The detection threshold that was updated adaptively as the signal-to-noise ratio (SNR) was changed. Kalman filter and homomorphic filter were used to predict statistical variable of the bit and turbulence parameters, respectively. Simulation and the experimental results indicate that bit-error probability (BEP) performance of the system is greatly improved by an order of magnitude or more.

An IM-DD optical communication system at data rate of 100 Mbps is designed for links between low earth orbiting (LEO) and geostationary (GEO) satellites. It was constructed with a fibre-coupled LD transmitter and a Si-APD photodetector. The system used the NRZ format. The transmitter achieves 1W average output power with a combination of multiplex laser drivers. Due to the transmitter drastically increased output power, it allows improvement of the link budget with, at the same time, reduced telescope diameter and PAT requirements. The receiver consisted of a threshold crossing detector and a timing recovery subsystem. It achieved a bit error rate of 10^-7 at -47dBm received average signal power.

Non-line-of-sight (NLOS) optical scattering communication (OSC) is studied theoretically and experimentally. Making use of single scattering propagation model, properties of NLOS optical scattering channel are simulated numerically under some typical condition. The results show that the path loss of the channel is quite large, and becomes larger as apex angle of the transmitter and receiver increases. The results also show that the pulse transmitted from the source is broadened significantly after propagating in the NLOS optical scattering channel. It will limit the available bandwidth of the channel, and probably cause intersymbol interference in digital communication systems. Moreover, some elementary experimental facilities of NLOS UV communications are constructed. A UV digital communication system based on 254nm low pressure mercury lamp has been set up, and the BER of the system is about ~10^-4 when the transmitter apex angle is 60 degree and bit rate is 1200bits/s. and NLOS light propagation experiments were conducted by exploiting a 370nm UV light-emitting diode (LED). With the progress of devices based on semiconductor in UV band, NLOS optical scattering communication with small volume and low power may be achieved in future.

This paper addresses the problem about how to deploy different protection strategies in the multi-layer network to use resource efficiently and give protections perfectly. Generally, every protection strategy has its own merits and demerits. How to use the merits of the protections efficiently and avoid the demerits as much as possible. For this aim, giving different protections to different LSP requests is a good selection. In this paper, we define different classes of LSP requests in terms of transmission delay and give different protections to different classes of LSP requests. Then, we propose a novel QoS-aware multi-layer protection scheme which consider the o-e-o conversion and the hop for the high priority requests at the same time and only consider the hop for the low priority requests. Moreover, we present a new inter-class backup resource sharing strategy within the scheme. It allows low priority requests to use the backup space of high priority services and also allows the high priority request use all of the resource of the network firstly as the blocking probability increasing. A complete set of experiments proves that this scheme can effectively decrease the blocking probability and end-to-end delay, comparing with the multi-layer protection scheme without inter-class backup resource sharing.

A Grid is a very large-scale network computing system that can potentially scale to Internet size, and the network computing system can be viewed as a virtual computer consisting of a networked set of heterogeneous machines that agrees to share their local resources with each other. In this paper, we proposed a contention resolution scheme for supporting Grid services in the OBS network. The numerical simulation was performed to evaluate the performance of the proposed scheme.

Optical crosstalk imposes a major limit to the practical implementation of optical cross-connects (OXCs). Inraband crosstalk contributions in three types of OXCs topologies based on the dilated Benes (DB) and generally modified dilated Benes (GMDB) networks are investigated and compared. Numerical simulation and experimental results confirm that OXCs based on GMDB networks can eliminate intraband crosstalk influence effectively compared with OXCs based on DB networks.

We have theoretically investigated the transmission performance of the optical microwave up-conversion link by using a phase modulator and a dispersive fiber (standard single mode fiber). A theoretical approach has lead to the evaluation of the influence of dispersion on the 60 GHz radio-over-fiber (ROF) links. According to our theoretically analysis, the data signals carried by optical millimeter (mm)-wave after transmission along fiber suffer not only from fading but also from the time shift of the code edges due to the fiber dispersive, which limits the transmission distance of the optical mm-wave signals. The simulation results agree well with our theoretical analysis.

The transmission characteristics of the FSK/ASK combined modulation format system is investigated and analyzed experimentally and theoretically. IP packets can be efficiently optical labelled using the proposed scheme. Numerical simulation was taken to demonstrate the transmission performance of the combine modulation format which can be affected by the dispersion compensation ratio, received optical power, coupling coefficient of the coupler and the payload extinction ratio. The performance of the proposed scheme has been evaluated experimentally for a transmission of a 155Mibt/s FSK combined with a 10Gbit/s ASK signal. Results show that the proposed scheme is applicable and competent for label extraction and encoding processes.

We propose a novel scheme of high bit rate optical frequency shift-keying transmitter. Base on the periodic notch spectral properties of Mach-Zehnder delay interferometer and the carrier suppressing functionality of Mach-Zehnder modulator, a high-speed optical FSK signal can be simply generated with another phase modulator and a single wavelength laser source. The transmission characteristics of this FSK signal are investigated under varying dispersion management. Simulated results show that 40Gb/s FSK signal gives only 1dB penalty after 80 km SMF transmission link under the post-compensation management scheme.

Based on the theoretical model of the synchronization system with incoherent optical feedback, the influence of the internal parameter mismatch on the synchronized characteristics of the chaotic system has been investigated. The result shows that the chaotic system with incoherent optical feedback can be realized more easily than the complete synchronized system, and has higher security than injection locking synchronization system. Using encoding of chaos shift keying, the message can be hidden efficiently during the transmission in the system and decoded easily in receiver.

In this paper, we study the nonlinear limitation of 10Gbit/s NRZ electronic pre-distortion (EPD) system by simulating. We constructed an ideal EPD simulation system with all chromatic dispersion compensation in electrical domain in transmitter; the fiber link includes Erbium-doped Optical Fiber Amplifier (EDFA) and 50km single mode fiber (SMF) in each span. And a dispersion compensation fiber (DCF) compensation system as a comparing object, with the fiber link includes EDFA, 50km SMF and DCF in each span. In single channel case, we find the EPD system is more sensitive with (self-phase modulation) SPM effect than DCF compensation system; in wavelength division multiplexing (WDM) system with 100GHz channel space, the cross-phase modulation (XPM) effects in EPD system induces more penalty fluctuating than DCF system. This is due to the large power variations in the waveform after large dispersion precompensation necessary for EPD. By compensating SPM effect and chromatic dispersion simultaneous in electrical domain in transmitter ideally, we can suppress SPM effect successfully in single channel system; but for WDM system, XPM effect still induces larger penalty fluctuating than DCF system. Because we can not predict signal patterns of neighbor channel, that means we can not compensate XPM effect. So, the XPM effect is the final nonlinear limitation of 10Gbit/s NRZ EPD WDM system.

We experimentally and theoretically investigate the propagation of intense femtosecond pulse in a nonlinear medium, in which the dynamic process of small-scale self-focusing of intense femtosecond pulse is experimentally investigated. By using tabletop femtosecond laser, the pulse which is spatially modulated by the cross silk diffraction passes through the nonlinear medium (carbon bisulfide, CS₂). As the input power increases, the small-scale self-focusing of the pulse is obtained. By analyzing the contrast gradient of the beam, we can obtain the dynamic process of small-scale self-focusing. Finally, we find that the numerical simulations are in good agreement with experimental results.

The optical design and experimental results of a free space optical communication system operating at 2Gbps using 1550nm VCSEL were introduced. The optical transmitting system consists of three optical senders and an optical receiver and a photoelectric receiving circuit. An automatic tracking system was employed to eliminate the pointing error between communication terminals. Each optical sender was designed as Schmidt-Cassegrain antenna to collimate the laser beam. λ / 2 plate and polarization beam splitter were used to decrease the interference of astigmatism and reflection. The optical receiver consists of a wave filter, dense-lines Fresnel lens and a photoelectric detector. The system's duplex communication tests showed that the data transmission rate can reach 2Gbps, error rate less than 10^-9, signal-to-noise ratio greater than 8 under the condition of clouds sky (attenuation coefficient is -16 dB/km) as the transmission length is 2000m, data carrier laser of 1550nm. The system had much higher speed rate comparing to other insertion system such as copper wire (1.5Mbps), electric cable (5Mbps), DSL (6Mbps per route).

The atmospheric two-dimensional optical code-division multiple-access (CDMA) systems using pulse-position modulation (PPM) and Turbo-coded were presented. We analyzed the bit-error rate (BER) of the proposed system using pulse-position modulation (PPM) with considering the effects of the scintillation, avalanche photodiode noise, thermal noise, and multi-user interference. We showed that the atmospheric two dimensional (2D) optical PPM CDMA systems can realize high-speed communications when the logarithm variance of the scintillation is less than 0.1, and the turbo-coded atmospheric optical CDMA system has better bit error rate(BER) performance than the atmospheric optical PPM CDMA systems without turbo-coded. We also showed that the turbo-coded system has better performance than the multi-user detection system.

We numerically investigate the autocorrelation characteristics of the linear chirped double-side exponential pulse and their variations affected by the chirp and noise, compare with the relevant parameters of the exponential pulse, give a useful method of filtering the random noise.

Token scheme is one of methods to overcome burst collision problem in Optical Burst Switch Ring Network with Fixed Transmitters and Tunable Receivers, but it brings big End-to-End delay and decreases bandwidth utilization. In this paper a novel token protocol is proposed, which can make better performance on End-to-End delay and bandwidth utilization.

Based on the analysis method of the light propagation in isotropic absorption media, the vector propagation constant is introduced and the light propagation in the biaxial absorption crystal is analyzed. The representations of some important physical parameters are derived, which was used to describe the crystal property and light propagation property, such as angle of refraction, refractive index, absorption coefficient. The corresponding results of transparent crystal can be deduced from these representations. When the crystal is absorptive, the reflection and transmission coefficients derived from the vector propagation constant method are in concordance with the results of complex refractive index method. So these two methods are uniform in some aspects, but the method of vector propagation constant is more convenient and available.

The simulating technique is used to investigate generating and distributing Ultra-Wide-Band signals depend on fiber transmission. Numerical result for the system about the frequency response shows that the characteristics of band-pass filter is presented, and the shorter the wavelength is, the bandwidth of lower frequency is wider. Transmission performance simulation for 12.5Gb/s psudo-random sequence also shows that Gaussian pulse signal after transported in fiber is similar to UWB wave pattern mask of FCC in time domain and frequency spectrum specification of FCC in frequency domain .

Modulational instability (MI) of electromagnetic waves in nonlinear birefringent step-wise decreasing fiber with co-existence of cubic and quintic nonlinearity is investigated by the coherently coupled nonlinear Schrödinger equation. The properties of MI gain are studied. The results show that, the procedure occurred not only in the normal dispersion regime but also in abnormal dispersion regime. The positive quintic nonlinearity index intensifies the modulation instability, making the width of the gain spectra of MI become wider and the peak gain higher, otherwise, suppresses the modulation instability, MI gain changes according to the distance propagated, and the gain spectra will change with token distance series.

During the information era, the Internet and the service of World Wide Web develop rapidly. Therefore, the wider and wider bandwidth is required with the lower and lower cost. The demand of operation turns out to be diversified. Data, images, videos and other special transmission demands share the challenge and opportunity with the service providers. Simultaneously, the electrical equipment has approached their limit. So the optical communication based on the wavelength division multiplexing (WDM) and the optical cross-connects (OXCs) shows great potentials and brilliant future to build an optical network based on the unique technical advantage and multi-wavelength characteristic. In this paper, we propose a multi-layered graph model with inter-path between layers to solve the problem of multicast routing wavelength assignment (RWA) contemporarily by employing an efficient graph theoretic formulation. And at the same time, an efficient dynamic multicast algorithm named Distributed Message Copying Multicast (DMCM) mechanism is also proposed. The multicast tree with minimum hops can be constructed dynamically according to this proposed scheme.

Electronic dispersion compensation (EDC) has recently gained attention as a cost-effective, power-effective solution used to counteract the distortion occurred in fiber optical communication system Transmitter side EDC (EDC-TX) and receiver side EDC (EDC-RX) are investigated in optical system for NRZ pulse shape and RZ pulse shape. The results show that each EDC mechanism has its corresponding preponderant effective range, for every pulse format.

We have both numerically and experimentally studied femtosecond chirped optical pulse undergoing self-focusing and splitting into multiple filamentation passing through carbon disulfide (CS₂). From the experimental results, we obtain that broad bandwidth laser pass through a nonlinear medium (CS₂) will occur modulation increase at the particular spatial position, and it shows good agreement with the simulation results. When the width of pulse increases (equal to the value of chirp add), modulation increase of chirped pulse beam will delay. After the modulation increase reaches to a certain value, it will stop increasing and appear new modulation frequency which bring optical beam to split into filamentation.

Antenna, which whether transmits or receives correct signal or not is our main care and our direction, is an important part in any wireless communication systems. Because of the characteristics of laser different from radio, the antenna system of point-to-point laser communication system must be designed strictly. In this paper, we mainly study the optical system in the inter-satellites laser communication. We compare with three kinds of optical antennas: refractor and reflector and Catadioptrics of the passive optical system; we also analyze the effect of bandwidth to the WDM communication systems; we use the correlative software, simulate the curves of the performance of the optical antennas. These analyses will be the base of the system of WDM laser inter-satellites communication.

The optical field distribution of TEo in the waveguide grating coupler is obtained by the vector two-dimensional finite difference time domain (FDTD) method. The calculated results indicate that the same optical field distribution and stable mode pattern can be obtainable through the different kinds of driving sources. It is found that the optical mode is determined by waveguide structure and dielectric parameters rather than the categories of incident light sources. These results are direct-viewing and accurate, and can be quickly obtained. According to the mode field distribution, the optimum coupling efficiency can be predicted. The results by this method agree very well with those of published papers by different algorithms, but the CPU-time and memory elements of computer used by FDTD are much less.