Resonant structures for band-operation optical modulators were investigated in this paper. Modulation efficiency was enhanced by the resonance of the modulating electrode. We can optimize the resonant structures by using equivalent circuit model and numerical electro-magnetic analysis such as the finite element method. The electric field distribution on the electrode was directly measured by the EO sampling technique.

Sophistication of the transmission format for 40-Gbit/s/ch WDM networks is indispensable. In long-haul transmission applications, the selection of transmission format should be a principal issue. In this paper, we overview several transmission formats regarding tolerance for fiber nonlinearity, group velocity dispersion, polarization mode dispersion, and spectral efficiency. We address and describe the superior performance against these impairments and high spectral efficiency of carrier-suppressed RZ and its related formats. The special spectrum structure of these formats enables a novel mode-splitting detection scheme. The scheme realizes variety of impact on 40-Gbit/s/ch WDM applications; expansion of dispersion tolerance, automatic dispersion compensation, and BER improvement by adopting a novel frequency diversity receiver.

In this paper, we discuss the potential for advanced modulation and electronic signal processing techniques to remove key barriers to commercially viable, near-term deployment of multi-Tb/s link capacities utilizing 40 Gb/s optical transport.

Bossnet is an in-ground testbed for developing optical networking techniques that enable new applications. The use of in-ground fiber (as opposed to laboratory experiments) allows new applications that require high data-rate communications over long distances to be tested. For the experiments described here, the light path includes ten spans of optical fiber with distances varying between 40 km and 73 km located on telephone poles and in the ground near railroad tracks and roadways. After each link, the light is amplified, filtered, and chromatic dispersion compensated. The experiment operates one 40-Gb/s RZ (return-to-zero format) channel at 193.5 THz and seven other channels with 10-Gb/s NRZ (non-return-to-zero format) modulation over a distance of 295 km from Lincoln Laboratory to New London, CT. These channels are

The optimum signal format and the optimum FEC code rate for 40 Gbit/s-based WDM systems have been studied experimentally and numerically. We found that the bandlimited CS-RZ with highly efficient FEC of between 80 % and 90 % code rates is expected to be a suitable solution for ultralarge-capacity long-haul 40 Gbit/s WDM systems.

We propose and evaluate a new return-to-zero (RZ) transmission format, which simplifies the transmitter and produces significantly improved eye diagrams at the receiver compared with other formats. By applying synchronous square wave phase modulation (PM) to a continuous wave (CW) signal, with a 180 degrees phase shift (phase reversal) between adjacent bit slots, and followed by an optimally tuned optical filter, we generate a train of RZ pulses which is inherently stable and resistant to dispersive and nonlinear effects. Separate amplitude modulation (AM) is unnecessary in this approach to shape the RZ pulses. This format (which we term CWSW) not only suppresses the growth of spurious pulses on adjacent "1" states, but also results in a peak intensity enhancement where waveform distortion caused by fiber dispersion initially improves the eye opening during transmission. Single-channel 40 Gbits/s systems employing dispersion-shifted fibers are investigated by computer simulations. We show that spurious pulse suppression and peak intensity enhancement increase the maximum transmission distance and improve the eye profile at the receiver relative to alternative transmission formats.

Subcarrier Multiplexed (SCM) systems have received a considerable amount of interest, mainly in areas such as radioon-fiber systems and multi-channel video distribution. SCM systems, which use double sideband transmission, however experience high dispersion penalty especially in long distance transmission. Several techniques have been proposed to improve this, one of which is optical single sideband modulation. Recently, a tandem single sideband (TSSB) technique that enables transmission of different channels on each of the two sidebands was proposed. This effectively doubles the bandwidth efficiency while improving the dispersion penalty. In this paper, we demonstrate a novel technique to transmit and receive in the proposed TSSB technique using orthogonal carriers. Two channels of 200 Mb/s NRZ data were used to modulate a pair of orthogonal RF carriers and subsequently transmitted using the TSSB technique. Although the RF spectrum of the two received channels overlaps one another, they can be separated using quadrature demodulators. In this paper, we report simulation results of error free transmission for two 200 Mb/s channels using orthogonal carriers in TSSB systems.

Technical possibilities to increase the capacity and distance in long-haul transmission systems are summarized and discussed. Based on the current status of commercial available performance and its extension, trends and trade-offs of capacity and distance are summarized with the consideration of OSNR. The dependence on repeater spacing and spectral efficiency is also summarized and discussed. Limiting factor of increasing capacity-distance products are described from the viewpoint of higher spectral efficiency and broader optical bandwidth. Several limiting factors such as OSNR, nonlinearities, dispersion and PMD are discussed with the candidates of solving technologies.

Advanced optical fibers enable high-capacity transmission for long reach systems and help to retain margin for networking. To do this they must support broadband operation, reduce nonlinear impairments, enable distributed gain and simplify networking. Here we describe fibers that incorporate dispersion management to extend span length and system reach over a broad bandwidth by compensating dispersion slope, reducing nonlinear impairments, and optimizing noise figure.

This paper identifies the sources of inefficiency for both transparent and opaque networks. The disparities in strategies for optimizing transparent and opaque networks are discussed. Strategies used for optimizing transparent optical networks include sub-wavelength edge grooming, optical access techniques with hub grooming, astute wavelength allocation and reuse, selective wavelength conversion and re-grooming preferably at the natural regeneration sites, use of tunable devices, multi-bitrate and multi-reach transmission in the same infrastructure, and system upgradeability from point-to-point to transparent networks.

The progress of DWDM transoceanic transmission technologies enabled the immense capacity transport of the submarine cable networks and dramatically decreased the unit capacity cost. However, in order to cost-ffectively transport the large capacity traffic using the submarine cable link, the study on the network architecture will be of great importance in terms of the reduction of the system installation cost and its associated operation cost. In addition, the change of the submarine cable network requirements is another driver to investigate the submarine network aspect.

Capacity upgrade of already installed undersea cable system is attractive from the cost point of view. Advanced technologies such as powerful forward error correction support this upgrade. In this paper, we demonstrate a system capacity upgrade beyond the designed limitation experimentally using the advanced technologies. As a result, a possibility to triple the designed capacity of trans-Atlantic system is shown. In addition, we propose a configuration to improve the transmission efficiency of the network combined with the expansion of the already installed undersea cable system.

By use of novel technologies for broadcast and select (B&S) node architecture and a dispersion-managed fiber system, we demonstrate an ultra-long-haul (ULH) network system consisting of 13 optical add/drop multiplexers (OADM) in an optically transparent 4160-km network chain. All 80 channels at a bit rate of 10.7-Gbps, spaced with a 50-GHz wavelength grid, perform >13.6 dBQ, which offer a 2-dBQ optical margin when forward error correction is applied. A dynamic spectral equalizer with 40 dB extinction ratio is used for the B&S OADM, which offers simultaneous blocking and leveling functions for channel drop and power equalization. The cross-talk penalty requirement of an OADM in the ULH system is studied.

We propose distributed Raman amplifiers (DRAs) for optical add/drop multiplexing (OADM) networks in order to suppress optical surges due to add/drop multiplexing. We confirmed that the fast transient characteristic of distributed Raman amplifier realizes no surviving channel degradation under add/drop power fluctuation condition as well as fine band upgradability to support "pay-as-you-grow" feature. And we also propose some application in metro area network by using DRAs.

The integration of electronic routing functions with WDM functions in network elements capable of reconfiguration over short time scales enables access networks to efficiently service time varying demand. An effective coordination of electronic and WDM network functions allows traffic to bypass electronic to optical conversion within the access network. The cost benefits derived from reduced transponder use due to this coordination can result in lower cost access for end users. The transparency of WDM also allows heterogeneous traffic formats to be carried over a common fiber. In this paper, we describe a reconfigurable WDM access network testbed that incorporates features outlined above. This testbed was used in demonstrating network functions such as dynamic lightpath provisioning, packet flow-switching, and remote amplification for supporting large numbers of end users. The testbed network incorporates protection switching and network control capabilities. The testbed network also provides connectivity to an in-ground long haul network. The testbed architecture and description of networking experiments demonstrating its capabilities are presented. The throughput degradation due to optical flow switching for Transport Control Protocol (TCP) data transmissions over large bitrate-delay product links is characterized. Adding the Eifel Algorithm to the TCP implementation restored performance. The performance of a remotely pumped EDFA for serving many users in the collection/distribution network is also presented.

The network paradigm is changing rapidly spurred by the dramatic increase in IP traffic and recent progress in photonic network technologies. A key requirement, enhancing the performance of existing IP-based multimedia communication networks, can be most effectively achieved by introducing optical path technologies that exploit wavelength routing. Cost effective and reliable optical cross-connection is essential. Different optical switch technologies have been proposed and tested. Among them, the PLC (Planer Lightwave Circuit) switch has demonstrated excellent performance, particularly with regard to system reliability. Network control mechanisms based on the overlay and peer model models have been developed. The presentation will highlight some of the key system technologies. To develop very large scale and robust networks, effective traffic engineering capabilities are necessary. This will be achieved through optical path control. To develop future IP-centric networks, an operation mechanism based on distributed control is important. The degree to which the necessary transport and IP routing functions are integrated will determine system cost-effectiveness. The Photonic MPLS (Multi Protocol Label Switching) router, which integrates all the functions and provides seamless operation between IP and optical layers, has been proposed and developed. The technical feasibility of a recent prototype system has been proven. Finally, some of the cutting-edge photonic transport technologies that we have recently developed are demonstrated; these technologies will enable us to achieve another level of network performance enhancement in the future.

Current IP/ATM routers use an electrical switching fabric/backplane and either optical or electrical interconnects between the line cards to route data. An electrical backplane and associated connectors limit the number of high speed interconnections due to practical considerations. Scaling these so-called third generation routers to the terabit regime with high port densities faces enormous problems due to the high interconnect and electrical power density. Packet routers with an optical switching fabric are considered as the next generation of IP/ATM Multi-Service routers which enable scalability towards the Terabit and Petabit regime. In this paper, various architectures with electrically active or passive optical switch fabrics will be highlighted and differences in terms of switching speed and scalability will be discussed. Recent results using a passive Array Waveguide Grating (AWG) router and fast wavelength tunable laser are presented in the second half of this paper.

Internet backbone network is undergoing a large-scale transformation from the current complex, static and multi-layer electronic-based architecture to the emerging simplified, and dynamic and one-layer photonic-based architecture. The explosive growth in the Internet, multi-media services, and IP router links are demanding the next generation Internet that can accommodate the entire traffic in a cost-effective manner. There is a consensus in current industries that IP over WDM integration technologies will be viable for the next generation of the optical Internet where the simplified flat network architecture can facilitate the networking performance and the networking management. In this paper, we firstly propose a novel node architecture-Terabit Optical Router (TOR) for building the next generation optical Internet and analyses each key function unit of TOR including multi-granularity electrical-optical hybrid switching fabrics, unified control plane unit and so on. Secondly, we give the unified routing definition of multi-layer in TOR and present control plane software structure with emphasis on multi-layer routing issues. Thirdly we describe our cost vs. performance analysis for various application of TOR. According to our calculation, we can get a cost reduction of more than 60 percent by using the TOR. Finally, we reach conclusions that TORs rather than OBS/OPS-based optical routers or big fat router, a cost effective multi-granularity switching and routing technique, are feasible to build the next generation Internet in the coming 5-10 years.

We are developing photonic packet switching system called multi-wavelength label switching node (Ml-LSN). This is a desired system to build ultra high-speed packet switching. The Ml-LSN analyzes the label all-optically. The photonic packet switching can be achieved with a help of optical packet with a multi-wavelength label. Different from an optical cross-connect (OXC) in a wavelength routing network, the Ml-LSN inherently has fine granularity. The Ml-LSN consists of photonic forwarding (label lookup), photonic switching, electronic scheduling, and photonic buffering. We describe demonstrations of photonic packet routing using the forwarding and the photonic switching in the Ml-LS. We report recent developments in the photonic packet routing based on multi-wavelength label switch. All-optical functions, variable data rate switching, variable length packet switching, label swapping, and label merge (replacing multiple labels by a single label) are demonstrated. We describe multi-stage fiber delay line buffer architecture to compensate for gap between electronic scheduling speed and optical data rate.

For DWDM networks, optical burst switching has been proposed as a combination of the best of optical circuit switching and optical packet switching while avoiding their shortcomings. One of the most challenging aspects of implementing burst switching DWDM networks is the design of data channel scheduling algorithms for core routers. In this paper, we present a channel scheduling algorithm, discuss its hardware implementation issues, and propose a hardware design.

Optical switching fabrics based on 3D MEMS technology potentially offer a scalable solution for the cross-connect network element. The design, integration, and assembly of high port count switch fabrics that can operate under a low loss budget, fast switching time, superb mirror stability and long-term reliable packaging present important engineering challenges. In this paper we describe the major optical, mechanical, MEMS and electronic design considerations as well as their critical inter-relationships in the development of 3D MEMS-based optical cross-connect fabrics. The specifications placed on the various components in order to meet the overall system tolerances and loss budget will be discussed. In addition, we will address the short-term (sub-millisecond) control and long-term (hours and up) stability of the optical connections due to mirror stability and long-term mechanical drifts. We will also present our thoughts regarding the solutions to those problems.

Generalized Multi-Protocol Label Switching (GMPLS) extends MPLS signaling and Internet routing protocols to provide a scalable, interoperable, distributed control plane, which is applicable to multiple network technologies such as optical cross connects (OXCs), photonic switches, IP routers, ATM switches, SONET and DWDM systems. It is intended to facilitate automatic service provisioning and dynamic neighbor and topology discovery across multi-vendor intelligent transport networks, as well as their clients. Efforts to standardize such a distributed common control plane have reached various stages in several bodies such as the IETF, ITU and OIF. This paper describes the design considerations and architecture of a GMPLS-based control plane that we have prototyped for core optical networks. Functional components of GMPLS signaling and routing are integrated in this architecture with an application layer controller module. Various requirements including bandwidth, network protection and survivability, traffic engineering, optimal utilization of network resources, and etc. are taken into consideration during path computation and provisioning. Initial experiments with our prototype demonstrate the feasibility and main benefits of GMPLS as a distributed control plane for core optical networks. In addition to such feasibility results, actual adoption and deployment of GMPLS as a common control plane for intelligent transport networks will depend on the successful completion of relevant standardization activities, extensive interoperability testing as well as the strengthening of appropriate business drivers.

We discuss a number of operation and maintenance (OAM) issues in optical burst-switched (OBS) networks and propose an OAM framework in this respect. Four OBS functions are identified as bases for the proposed framework. These are the burst termination function, the burst transmission function, the switching function, and the routing and switching control function. The study focuses on the unique aspects of OBS networks and how they can be addressed from an OAM point of view. We propose an OAM architecture and investigate the functional, network, and node aspects of it. Novel OAM-capable structures for core and edge OBS nodes are introduced for the first time.

Optical network Survivability in the backbone, or core, network has been an active area of research. As optics move closer to the edge and to end users, the core network is now used not only to provide connections across a wide area,but also to provide connections for local and metropolitan area networks (LANs and MANs). While optical backbone networks are generally concerned with providing end-to-end circuits based upon whole wavelengths, optical LANS and MANs generally provide shared access to a small number of wavelengths. In this paper, we consider the issue of robustness for optical access networks built as overlays on optical mesh networks. The problem of optical access network robustness is that of maintaining connectivity among nodes of the access networks after a link (or possibly node). We survey three methods of providing robustness to optical access networks. The first method consists of building access networks as covers of rings. The second method builds folded bus overlays and use a combination of optical switches and electronic routers to provide reliability. The third generalizes the concept of buses to build tree-based robust collection and distribution routes over mesh networks. Optical access networks are beginning to be deployed at the edge of the optical backbone network to support access by the high-end users that drive increased bandwidth demands. This development in the applications of optical networking poses new challenges in the areas of medium access, topology design and network management. In this article, we survey access network architectures and outline the issues associated with providing reliability for these architectures.

Protection using rings has been the common method of reducing downtime on SONET/SDH based telecommunication networks. With the trend towards IP over DWDM, there is a need for IP based protection and restoration mechanisms. In this paper, the mechanisms being developed at several standards organizations including OIF, IETF, and ITU are described. These mechanisms are in some sense more powerful than the previous SONET/SDH based mechanisms and protect against not only link and node failures but also against domain failures. Here domain refers to an entire region of the network. In particular, Shared Risk Group (SRG) concepts being developed at IETF and OIF is explained.

This paper surveys recent progress in optical protection rings with the focus on transparent optical protection rings. Generic requirements and attributes for optical protection rings, different optical protection ring architectures such as dedicated and shared protection rings in both the optical channel layer and the optical multiplex section layer are described. In particular, optical channel shared protection rings are discussed in detail including node architecture designs, ring protocols, triggers and messaging channels. Feasibility studies and experimental results from Corning Incorporated and other companies are reviewed. The paper also discusses how protection switching times scale with number of nodes and number of wavelengths, and shows examples of applications using the scaling rules for practical optical networks such as metro, regional and long haul ring network. Finally, the paper discusses remaining issues and future developments in the optical protection ring area.

Due to increasing traffic demands telecommunication operators have to upgrade the transmission capacity of their networks. Since the success story of WDM in optical fiber based networks, component and system manufacturers as well as operators are dealing with the question if it is better to increase the number of WDM channels remaining at low channel bitrate or to enhance the channel line rate itself. The momentary situation is that already 10 Gbit/s based systems are installed for client traffic and are running properly. By a comparison of the technical advantages and business cases for a lot of transmission scenarios, the 10 Gbit/s solution turns out to be the preferable solution if compared to 2.5-Gbit/s-based systems. In the meantime 40GHz electronics has made severe progress so that now it seems to be possible to take the step towards the next hierarchy, the 40 Gbit/s channel rate. Nevertheless, many system manufacturers still wait with the market introduction of 40 Gbit/s, on the one hand because we observe a stagnant capacity demand this year, and on the other hand because the business case seems yet not to be competitive. One of the reasons for this is the impact of different physical limitations of fast optical fiber transmission. While the step from 2.5 to 10 Gbit/s still did not raise severe technological problems for medium distances, this is completely different for ultra long haul systems and especially for all 40-Gbit/s-based systems. While nonlinear effects still can be sufficiently managed, phenomena like, e.g., polarization-mode dispersion (PMD), chromatic dispersion mismatch, and gain tilt of optical amplifiers play an important role. Chromatic dispersion and polarization effects may vary with time so that either passive or adaptive compensation schemes may be needed in order to realize sufficiently long transmission distances. This paper will deal with different current solutions to overcome limitations from fibers and components, namely the use of special modulation formats, the use of pa

The design of optical communication networks with network switching elements operating in the optical domain requires careful system analysis and potentially stringent component requirements. We consider here network elements such as transparent optical cross-connects that demultiplex WDM signals, optically switch individual channels, and then multiplex the wavelengths together again before transmission into the next span. Network element optical impairments that can degrade signal quality are in-band (same wavelength) crosstalk, out-of-band crosstalk, and signal distortion from filter concatenation effects. These impairments can limit the transmission distance of a signal before regeneration is required. We examine the trade-offs between crosstalk and filter distortion in the context of the optical filters used in the optical multiplexers and demultiplexers in the network elements. We demonstrate the balance that must be struck between these impairment types in the design of the filters and network system. We study a 10 Gb/s network with 50 GHz channel spacing, examining both NRZ and RZ modulation formats. In both cases, we find optimal filter bandwidths that minimize the total signal degradation measured in terms of Q penalty. The total penalty suffered by RZ signals is higher than that of NRZ signals and must be considered when estimating system reach.

A fast spectral power equalizer was designed and tested in a reconfigurable optical network testbed. Its response time is ~100 microseconds. Dynamic power fluctuation caused by add/drop switching in reconfigurable optical networks can be compensated by this technology.

Management of dynamic DWDM networks requires a network-wide awareness of the status and health of optical channels. Optical Wavelength Managers (OWMs) are a new class of network element that enables the measurement of optical channel characteristics (power, wavelength and OSNR) at key locations in a DWDM network. OWMs also report these data to a Network Operations Center (NOC) for the purpose of performance monitoring and element management. This paper demonstrates the use of OWMs to provide distributed optical monitoring and active management of optical components/network elements in DWDM networks. Localized element management was demonstrated by using an OWM to automate power balancing of multiple wavelengths using an array of Variable Optical Attenuators (VOAs). A similar technique was used to control the wavelength drift of a transmitter laser. Distributed network management is also demonstrated by using OWMs and a VOA to adjust optical channel power levels required by a change in lightpath. These monitoring and management capabilities could enable automated supervision of DWDM systems and facilitate a carriers' ability to administer multiple service level agreements

An analysis of a 2R optical regenerator consisting of a saturable absorber, a highly nonlinear fiber, and an optical bandpass filter is presented. How the regenerator improves the performance of quasi-linear highly-dispersed pulse transmission and reduces the transmission impairment caused by polarization-mode dispersion is numerically studied.

Along with progresses in high-speed, broadband long-haul and full service transmission in optical fiber system, the polarization mode dispersion has become one of major limiting factors in terms of the system bandwidth and the linearity, and leads to severe signal impairments, especially the second-order PMD for an analog system. Therefore the purpose of the paper is to present a detailed description of PMD effects (in terms of composite second-order) on PAL-D 60 channels analog CATV signals and to show the numerical simulations about some important relations between the CSO and the PMD distortion factors. Based on the simulation results, we also discuss a second-order PMD compensation scheme for optical DWDM CATV backbone network, which can efficiently reduce second-order, or even higher-order nonlinear distortions. It has been successfully applied to our national CATV networks.

The fiber-optic channel introduces a number of linear and non-linear effects including dispersion (e.g., chromatic dispersion), attenuation, four wave mixing, and self phase modulation. As DWDM (Dense Wavelength Division Multiplexing) systems grow in bit rates per channel and numbers of channels, sensitivity to these effects increases. A recently-proposed, far-reaching solution to counter many channel effects is based on Carrier Interferometry (CI) ultrashort pulses. Specifically, at the transmitter, the Frequency Shifted Feedback Cavity (FSFC) is used to generate an ultra short CI pulse via the superpositioning of N equally spaced frequency components. This ultra short pulse is transmitted over the fiber to the receiver side, where the CI pulse is decomposed into its N frequency components. This enables (1) the cancellation of channel effects such as dispersion via the application of different phases to different frequency components; and (2) the use of low-speed (inexpensive) electronic components. Via dispersion compensation, guard time between adjacent pulses is greatly diminished, leading directly to higher data rates per channel. In this work, we demonstrate the robustness of the proposed CI fiber-optic system to errors in dispersion compensation, suggesting that even when the proposed CI system can not perfectly account for dispersion, it can still achieve excellent performances. This, in turn, indicates that even with imperfect dispersion compensation, guard intervals at the transmit side are still unnecessary in CI systems.

We proposed and demonstrated a bi-directional dense-wavelength-division-multiplexing (DWDM) CATV system which used chirped fiber grating (CFG) and large effective area fiber (LEAF) as dispersion compensation devices to reduce the dispersion and cross-phase modulation (XPM)-induced crosstalk. By comparing with the system link with a transmission length of 50 km single-mode fiber (SMF) without CFG, good performances of carrier-to-noise ratio (CNR) >50 dB, composite second order (CSO) >69 dB and composite triple beat (CTB) >66 dB were obtained in our proposed system over a 50-km LEAF transport.

The paper proposes free-space optics (FSO) as one of the potential solutions for the design and development of next generation, high-capacity, high-speed wireless networks. The hybrid wireless architecture is introduced and the role of FSO in the proposed architecture is highlighted. The significance of the hybrid architecture in achieving ubiquitous, carrier-grade wireless connectivity is also explained. The paper presents various FSO network design challenges and potential solutions for real-time FSO link performance characterization as well as dynamic FSO link adaptability for enhanced performance during adverse operating conditions. Dynamic power control and dynamic data rate control schemes are evaluated for FSO link adaptability. Dynamic load switching (DLS) scheme for hybrid architecture functionality during extreme conditions is also evaluated. Finally, the paper describes an elaborate field test-bed based on hybrid architecture, and various dynamic FSO link adaptation techniques implemented in to the test-bed. The performance of these dynamic link adaptation schemes and DLS functionality is presented to quantify the improvement in overall hybrid architecture performance. The results, recorded from the experiments during extreme weather conditions, validate the hybrid architecture concept and conclusively prove the reliability of the architecture in achieving sustained high-speed connectivity.

Eight Gigabit Ethernet channels are multiplexed to a 10 Gb/s stream and sent over 1020 km of in-ground fiber. By daisy chaining channels, longer Gigabit Ethernet paths are emulated. Bulk transfer at 947 Mb/s was demonstrated with computer separations of 2040 km using TCP.

A hybrid dense-wavelength-division-multiplexing (DWDM) system for CATV, 256-QAM and OC-48 trunking is demonstrated. It used two wavelengths for AM-VSB CATV, two wavelengths for 256-QAM digital passband signals and four wavelengths for OC-48 (2.5 Gb/s) digital baseband signals transport. Good performances of carrier-to-noise ratio (CNR) >50 dB, composite second order (CSO) >64 dB and composite triple beat (CTB) >63 dB were obtained for AM-VSB CATV; and low bit error rate (BER <10^-9) had been achieved for 256-QAM and OC-48 digital signals over an 80-km large effective area fiber (LEAF) transport.

Fiber optic based analog and/or digital CATV systems experience composite second order distortion (CSO) caused by the interaction between the gain tilt of the doped fiber amplifier and the laser chirp due to modulation. The gain tilt for an analog/digital transmission system using a high power Er-Yb co-doped fiber amplifier has been experimentally measured and its contribution to the CSO of the transmission system is evaluated. The results are in good agreement when compared with the direct measurement of the CSO of the system with and without the amplifier. The dependence of the gain tilt on the input light modulation frequency and the input light wavelength is also investigated.

One focus of study is how to improve and enhance signal performance in the field of data storage system.The technology on the signal processing has become more and more mature in conventional storage system, e.g. magnetic storage and optical storage. In holographic storage, data is accessed in accordance with page-by-page versus bit-by-bit in conventional methods. So, the more complex factors are existed to produce the signal distortion in volume holographic memory(VHM).As a result ,a new challenge in data storage arise in the front of some researchers engaged in signal processing.As the onventional method, It is necessary to develop an appropriate signal modeling. In this paper, similar work is greatlydesirable for VHM also. Specifically, a signal modeling for VHM is developed by means of analytic method.Simulation result show that a 6.83% density gain and 17.83% capacity gain in the low-contrast (C=5)can be result in when the aperture size is fixed in the trade-off aperture, On the other hand, the density and capacity is increased25.65% and 43.15% in the infinite contrast, respectively.

In this paper, we present the Optical Cross-Connect (OXC) Management Control System Architecture, which has the scalability and robust maintenance and provides the distributed managing environment in the optical transport network. The OXC system we are developing, which is divided into the hardware and the internal and external software for the OXC system, is made up the OXC subsystem with the Optical Transport Network (OTN) sub layers-hardware and the optical switch control system, the signaling control protocol subsystem performing the User-to-Network Interface (UNI) and Network-to-Network Interface (NNI) signaling control, the Operation Administration Maintenance & Provisioning (OAM&P) subsystem, and the network management subsystem. And the OXC management control system has the features that can support the flexible expansion of the optical transport network, provide the connectivity to heterogeneous external network elements, be added or deleted without interrupting OAM&P services, be remotely operated, provide the global view and detail information for network planner and operator, and have Common Object Request Broker Architecture (CORBA) based the open system architecture adding and deleting the intelligent service networking functions easily in future. To meet these considerations, we adopt the object oriented development method in the whole developing steps of the system analysis, design, and implementation to build the OXC management control system with the scalability, the maintenance, and the distributed managing environment. As a consequently, the componentification for the OXC operation management functions of each subsystem makes the robust maintenance, and increases code reusability. Also, the component based OXC management control system architecture will have the flexibility and scalability in nature.

When Light propagates through optical elements (such as lenses), it undergoes a transform. The input and the output data take the form of light and optical elements that perform different mathematical operations on light represent the linear transform. The transform is performed not on the discrete elements of the data but on the whole vector at once, and most significantly, at the speed of light. The great advantages offered by optical processing are that it offers enormous parallelism, operating on all data points simultaneously, very low latency, a high transform rate and low power dissipation. The outcome is enormously increased speed and a reduction in the amount of associated cooling required. The Optical Signal Processor (OSP) increases the speed of processing transforms by many orders of magnitude. The Signal Processor is also reconfigurable and can be dynamically tailored to the required transform type. One advantage of an optical processor is that it allows software designers to work at a much higher level of abstraction. This is because the device executes transforms instead of the ordinary MACs in the case of DSPs. Instead of handling algorithms at individual data points, algorithms for handling the entire vector could be processed, shortening the computational complexity and speeding the time-to-market for new products. An optical filter can be represented as a generic function, the most fundamental of the optical processor. The impulse response of this filter is defined with respect to frequency of light. Any transform on light can be represented as a combination of linear transforms. This is fundamentally the law of optical signal processing. The most important application of an OSP in Optical Networking is Pattern recognition, and this can easily be done by the usual cross-correlation technique that is common in digital signal processing. The OSP can be programmed to autocorrelate against specific temporal reference waveforms, viz. Data. The decoding is done without electronic processing. And of

Optical label switching is a promising optical packet switching technology to ease the process of getting the route information from the packet label in optical domain. In this paper, a promising kind of multi-wavelength label is adopted and to which a simple label extraction and recognition technology through a array of tunable Fiber Bragg Gratings (FBGs) is presented.

We analyzed linear and nonlinear properties of non-return-to-zero (NRZ), return-to-zero with 50% duty cycle (RZ50), return-to-zero with 33% duty cycle (RZ33), carrier-suppressed return-to-zero CSRZ, and differential phase shift keying (DPSK) modulation formats in order to predict the comparable advantages of their implementation in 40Gb/s WDM systems. We showed the advantage of RZ type formats over NRZ results from the trade off between better nonlinear tolerance and linear impairments such as inter-channel cross-talk and dispersion penalties. We estimated that in 40Gb/s 0.4 spectral efficiency WDM system on 10 100km spans of standard single mode fiber RZ33 format has Q value 1.5dB higher than NRZ. We also found that in a such system DPSK with controlled chip outperforms RZ33 by 0.8dB Q due to the difference in limiting nonlinear impairments and superior linear properties.