This PDF file contains the front matter associated with SPIE Proceedings Volume 12429, including the Title Page, Copyright information, Table of Contents, and Conference Committee information.

We have proposed a new approach for photonic-assisted arbitrary waveform generation in beyond 5G taking advantage of low frequency technology. The generated signals in low frequency technology can be temporally compressed by a chromatic dispersion toward millimeter wave and terahertz band high frequency region. To the best of our knowledge, our recent proposed approach for beyond GHz-class AWG using the MHz-class low-frequency technology with photonic assistance based on chirped pulse compression is first proposed to remodel it to obtain competitive performances in signal frequency, as well as analog resolution, cost, and power consumption. Various use cases in beyond 5G, a large number of signal from massive edge subsystem should be bundled. This requires a signal processing for aggregation of multi-data from vast multi-user information as well as data compression. The data signal is digitally processed for segmentation and tuning so as to accommodate it in the stretched carrier pulse according to the length of signal. Since signals become sparse in beyond-GHz region after signal compression, the produced temporal free space in a frame could be used for accommodation. Such a produced temporal free space can be used for accommodation of overflowing data and users. This requires an additional signal processing for aggregation of multi-data from vast massive user information as well as data compression. In this work, we propose the photonic data aggregation technique for millimeter wave and terahertz band high frequency migration technology for beyond 5G.

Photonic integrated circuits (PICs) are one of the key enablers for beyond 5G networks. A novel generation of fully integrated photonic-enabled transceivers operating seamlessly in W- D- and THz-bands is developed within the EU funded project TERAWAY. Photonic integration technology enables key photonic functionalities on a single PIC including photonic up/down conversion. For efficient down-conversion at the photonic integrated receiver, we develop the first waveguide-fed photoconductive antenna for THz communications. Finally, we report on the experimental implementation of a fully photonic-enabled link operating across W- D- and THz-bands.

For the first time, we have experimentally demonstrated an all-silicon polarization-multiplexed IQ modulator targeting 800ZR pluggable transceivers for data-center interconnection. Using realistic DAC, ADC, DSP, and commercially available driver amplifiers, we can achieve an equivalent transmitter output power of -15.74 dBm and an rOSNR of 26.51 dB with oFEC. Furthermore, a superior performance showing a transmitter output power of -13.55 dBm and an rOSNR of 26.6 dB can be achieved by using a future co-packaged driver chip with peaking capability, which is experimentally emulated by an optical spectral shaper. In addition, an optical sub-assembly consisting of co-packaged a SiPho chip and a TIA chip is under sample building and testing. The demonstration paves a way for near-term available 800ZR pluggable transceivers based on silicon photonics.

This conference presentation was prepared for SPIE OPTO, Photonics West, 2023.

Hierarchical spatial bypassing and spectral grooming in recently proposed spatial channel network (SCN) architectures are beneficial in the space division multiplexing era in terms of reducing the total node cost while maintaining a reasonably high spectral efficiency and optical-reach extension for optical signals that spatially bypass the overlying wavelength division multiplexing layer. One key piece of equipment to achieve SCNs is a spatial cross-connect (SXC). In this paper, enabling technologies for flexible and scalable SXCs including a core selective switch, a multicore fiber splitter, a core selector, and a core/port selector are reported.

Silicon photonics is now considered the photonics platform of choice for short-reach data center single mode pluggable transceivers. With the emergence of co-packaged optics concepts, it can also enable high performance computing with power-efficient interconnect, but also Lidar system integration or even optical quantum computing. In this paper we will present an overview of what can be achieved in state-of-the-art silicon photonics platforms and we will discuss some of the emerging technology trends. In particular, we will discuss the integration of LPCVD SiN in an active silicon photonics platform.

Undersea submarine cable transmission systems are characterized by fixed and limited electrical power supplies. Electrical power is provided by a DC voltage applied across the cable from power feed equipment (PFE) located at the terminal ends and is used to power all optical amplifiers throughout the entire link which may be many thousands of kilometers. Because of the limited nature of electrical power, the concept of power efficiency is very important. In fact, power efficiency drives the recent design trend in undersea systems to spatial division multiplexing (SDM), increasing fiber counts in submarine cables. We examine here efficiency maximization via system modeling primarily with respect to the optimal generalized signal-to-noise ratio (GSNR). We explore dependences on system aspects such as capacity metric, link length, span loss, and fiber attenuation. We compare three different measures of efficiency based on total amplifier optical output power, total pump power, and overall cable capacity predicted by application of a pump sharing model and the resulting electrical-to-optical conversion efficiency levels predicted. Several capacity metrics are also studied and compared ranging from the theoretical Shannon capacity limit to a fitting of a real-time transponder. We evaluate optimal link GSNR values that maximize the various efficiency definitions as a function of link length, as well as optimal span loss values for a fixed link distance.

A multicore fiber (MCF) with the standard cladding diameter is expected to be deployed in the early stage of a spatial division multiplexing-based transmission system. Inter-core crosstalk in an MCF is closely related to the bending conditions, so it is expected to vary with the deployment conditions. The bending radius dependence of the crosstalk can be modeled in accordance with the power coupling theory. In this paper, we experimentally investigate the crosstalk property variation among spooled, cabled, and installed MCFs and show that the crosstalk increases slightly in the cabled and installed conditions compared to in the spooled fiber. We numerically examine this crosstalk change by considering the power coupling theory and actual bending conditions in a high-density optical cable. Our findings reveal that the crosstalk change during the cabling and installation processes corresponds to a change in the bending state, and that the crosstalk after installation has a good correlation with the effective bending radius in the cable.

This conference presentation was prepared for SPIE OPTO, Photonics West, 2023.

The required information volume in the ICT market is increasing faster than expected, and ultra-high-speed optical transceivers/optical components with transmission speeds of 400G or higher are rapidly being put into practical use. Along with higher speeds, these optical transceivers/components are required to be smaller and have lower power consumption, requiring the application of optical integration technology and fine CMOS processes. Under these circumstances, international forum standardization organizations such as IEEE802.3/OIF have started standardization of ultra-high-speed optical transceivers beyond 800G by 2021. In this report, we will focus on the latest topics of the standardization organizations and address the issues toward practical application of 800G/1.6T.

A 3-mode fiber with pure silica core and dual-step index profile is numerically investigated for realizing low DMD and low loss. We found a structure that minimizes DMD while maintaining the low loss property of the pure silica core. We also show that lower loss and larger MFD properties are restricted by the requirement for the micro-bending sensitivity.

We revisit the design strategies of erbium-doped fiber amplifiers (EDFA) in wavelength division multiplexing (WDM) submarine links over transoceanic distances. We particularly investigate the optimization of EDFA settings such as fiber length, optical bandwidth and population inversion to maximize the power efficiency and/or achievable information rate (AIR) at fixed span length. When optical bandwidth is fixed, we show the existence of a unique EDFA optimum setting whatever the pump power, provided Kerr-effect is overlooked. When accounting for Kerr-effect, the EDFA parameters can be adjusted to improve AIR as pump power increases. We also show a performance enhancement when working with a variable bandwidth design at very-low and very-high pump powers.

The transmission capacity of a fiber communication link is determined by many factors, among which the characteristics of the optical amplifiers used to boost the signals. Semiconductor optical amplifiers (SOAs) present their unique set of challenges. The noise figure and polarization dependent gain of the SOA is typically a bit higher than that of its fiber amplifier counterparts, and its fast gain dynamics potentially triggers non-linearities that may cause crosstalk between different WDM channels. We will discuss how these factors limit the capacity in WDM transmission with examples of both single span datacom amplification and high capacity cascaded transmission lines.

Distributed Fiber Optic Sensing (DFOS) systems rely on measuring and analyzing different properties of the backscattered light of an optical pulse propagating along a fiber cable. DFOS systems can measure temperature, strain, vibrations, or acoustic excitations on the fiber cable and to their unique specifications, they have many applications and advantages over competing technologies. In this talk we will focus on the challenges and applications of DFOS systems using outdoor grade telecom fiber networks instead of standard indoor or some specialty fiber cables.

To reduce costs and simplify operations, network operators are deploying the latest network devices that are power efficient and compact. In this paper, a detailed comparison is made between the design of a reconfigurable add-drop multiplexer (ROADM) based on an integrated circuit (PIC) and the state-of-the-art ROADM devices. In particular, the performance of the device in terms of frequency response parameters is presented in the paper in comparison with the state-of-the-art ROADMs. The proposed PIC based ROADM can operate in a multi-band scenario, including C+L+S bands, and is potentially scalable to many output fibers and routed channels while maintaining a small footprint. A detailed network performance analysis is performed with the proposed PIC-based ROADM device and its impact on the network. Due to increasing traffic demand, the current optical transport infrastructure is experiencing capacity problems: two possible solutions are Spatial Division Multiplexing (SDM) and Bandwidth Division Multiplexing (BDM), which both allow capacity expansion of the existing infrastructure. We have studied the network performance of the proposed ROADM device on the Spain-E network and performed a detailed comparison for the SDM and BDM scenarios. Compared to the SDM approach, which requires the deployment of additional fiber, the cost-effective BDM scenario can better utilize capacity without installing new fiber infrastructure or using dark fibers.

For monitoring high-speed optical telecom signals and/or spectrally broadened light waves, such as optical frequency combs, it is desired to measure the optical spectra with higher bandwidth and resolution. For the purposes, in this paper, we demonstrate a high-resolution and high-speed optical spectrum analyzer that only relies on a DSP operated at a much lower speed. This spectrum analyzer consists of two-stage spectroscopy systems, which is a diffractive grating system and a sampled heterodyne system. We experimentally demonstrate the spectral measurement with greater than 10-pm resolution at 100-kHz acquisition rate covering bandwidth of 5-GHz.

Submarine systems have recently evolved from turnkey systems into an open cable approach, where new metrics describing wet plant performance have been defined. The transmission GSNR has been standardized and is measured together with the OSNR in cable commissioning to characterize open submarine links. We propose in this paper a method based on numerical simulation to accurately predict the achievable capacity of open cables using only the commissioning parameters. We also assess the impact of the measurement uncertainties during commissioning on capacity prediction. Finally, we apply the proposed method to realistic subsea links and show how the uncertainty on the capacity estimate can be reduced further when using the commissioning measurements to reduce the uncertainty on line parameters.

The popularity of high-capacity communication services such as video streaming and cloud computing has accelerated the growth in IP traffic. In order to effectively manage and maintain networking systems, various intelligent technologies based on software-defined networking (SDN) have been widely studied. An SDN system that offers flexible optical path management exploiting optical performance monitoring, digital signal processing, and resource allocation is expected to realize higher capacity networks by lowering margins needed to offset system uncertainty. In this paper, we provide a comprehensive survey of optical path management schemes based on machine learning.

By employing a delay line signal processing technique, a mathematical model of an asymmetrical quad microring resonator (QMRR) can be calculated. Four asymmetrical rings are coupled with each other in vertically connected structures of QMRRs are designed. The performance of QMRR structures is demonstrated using two different types of waveguide bus, namely crossing and parallel waveguides. In the MATLAB environment, the frequency spectrum response and accompanying transmittance, phase, and group delay plots are programmed and graphically presented.

Based on Vehicle-to-Vehicle, Vehicle-to-Infrastructure and Infrastructure-to-Vehicle communications, we propose a VLC system for managing vehicles crossing a light controlled intersection in a safe manner. Connected vehicles and infrastructure interact by broadcasting information using headlights, streetlights, and traffic signals. Transmitters emit light signals encoded, modulated and converted from data. Optical sensors with light filtering properties are used as receivers and decoders. A joint transmission allows mobile optical receivers to collect data, calculate their location for positioning, and read the transmitted data at the same time. A communication scenario is stablished. Parallel to this, an intersection manager coordinates traffic flow and interacts with vehicles through embedded Driver Agents. To command the passage of vehicles crossing the intersection safely queue/request/response mechanisms and temporal/space relative pose concepts are used. A dynamic phasing diagram and a matrix of states based on the total accumulated time are presented to illustrate the concept. On a Simulation of Urban MObility simulator (SUMO), deep reinforcement learning was used to control the cycle of traffic lights. Data shows that the adaptive traffic control system in the V2X environment can collect detailed data, including vehicle position, speed, queue length, and stopping time. Dynamic control of traffic flows at intersections is demonstrated using sequence state durations, phase diagrams, and average speed measurements. For the same traffic flow, static and dynamic cycle lengths were compared. According to the results, the dynamic system finishes the cycle first by adjusting the durations of the cycles as necessary. The better temporal management of phases results in better traffic flow and a higher average speed.

Research of Yole Intelligence aims to give a comprehensive account of the forces driving the optical interconnects market, technology and industry. We provide macro trend analyses for both datacom and telecom, review the trends in data centers impacting the optical module market and elucidate comprehensive technology analysis of optical transceivers highlighting the trends for application from intra-data centers up to long-haul. Furthermore, evaluation of silicon photonics and InP technology platforms in term of technology and market dynamics is also reported. We analyze market and provide forecasts for revenue and volume of optical transceivers for 2017-2027 split by applications and speeds.

The optical frequency comb is a special light source that has spectral components of equal frequency intervals and is useful for various photonic measurements. In this paper, we propose a method to reduce the design and control difficulty of an etalon spectrometer, which is effective for optical frequency comb measurement. In the method, spectral data of the target optical frequency comb are obtained from a low-resolution etalon spectrometer by performing deconvolution data processing using the original algorithm called the inverse matrix data processing. This method makes it possible to measure the optical frequency comb more easily and cost-effectively.

We review recent advances in the design of wideband Raman amplifiers, describe their experimental performance evaluation in coherent transmission systems, and discuss their potential applications to wideband optical networks.

In the next fifth-generation (5G) and sixth-generation (6G) wireless cellular networks, the millimeter-wave band presents new possibilities for extremely strong data transfer speeds and extensive network connectivity. Millimeter waves, on the other hand, suffer from a large loss of propagation, which is the most severe obstacle. Utilizing beamforming with several antennas is a helpful solution to this problem, which may be overcome. In this article, a concept for an integrated photonic beamforming system is presented using ring resonator for 1 4 phase array antenna in Ka-Band. Signal operating at 28GHz is based on waveguide technology. The micro-ring resonator is utilized so that the actual time delay line can be achieved. The mathematical analysis and design of the beam forming structure are presented after that It was possible to produce a group delay of 250 ps, 500 ps, 750 ps, and 1000 ps delay of the proposed different cascaded architecture of ring resonator as a delay element which corresponds to a beam directing angle of 30° , 90° , 11.5° , 8.62° degrees respectively.

Spatial light modulators (SLM) are experimentally characterized to be used as reconfigurable-intelligent surfaces (RIS) for smart beam steering of multiple beams for indoor optical wireless communication application. The SLM surface is segmented into two separate regions to perform multibeam steering of two separate incident laser beams to two user devices. Beam steering is achieved here by applying blazed-grating and de-centered lens profile using liquid-crystal-onsilicon (LCoS) phase-only SLM. Experimental measurements of beam steering using blazed grating profiles results in ±3.6 ° steering. The first-order diffraction efficiency decreases from 54.5% to 21.8% for right half and 39.8% to 14.5% for the left half SLM with increase in steering angle as a function of decreasing in blazed grating pitch. The blaze grating-based beam steering is however prone to blind zones in which steering is not possible and the non-linear dependence of the steering angle on grating pitch. To overcome these limitations, we investigate de-centered lens profile as a mechanism to steer the beam. This results in a linear relationship between lens decentring of the lens profile and steering at high resolution. The measured resolution with this technique is ~0. 0018° /pixel with angular span of ±4.26° . The first-order diffraction efficiency is found to be varied from 40.1% to 8.5%. We have also designed additional magnification optics to further increase the above steering angle by a factor of 10-times using Zemax-based ray-tracing.

This paper proposes a mm-wave cellular flexible architecture based on a photonic beamformer network. An overview of integrated optical beamformer technology state-of-the-art is reported considering different implementations, fabrication technologies and the associated design requirements and limitations. A network architecture based on multicore-fiber (MCF) is proposed to operate as fronthaul or backhaul depending on the network configuration and user capacity dynamics. Multi-wavelength operation is achieved employing an optical frequency comb generator capable of providing several phase-correlated optical lines. Following new-radio 5G specifications, both NR 5G frequency ranges (FR) are considered in the proposed network, including FR1 at sub-6 GHz frequency bands, and FR2 in the mm-wave range from 24 to 100 GHz. The work analyses the main subsystems of the integrated photonics beamformer: the laser source which comprises an optical comb, the optical filtering and induced delay subsystems, the arrangement of MCF media to feed different antenna elements and the mm-wave generation subsystem, where optical heterodyning is proposed. The performance of these key subsystems is evaluated experimentally and analyzed by simulation when necessary to assess the proper photonic beamforming network operation.

This paper experimentally demonstrates the performance of subcarrier intensity modulation with polarisation division multiplexing (SIM-PDM) in a range of different water conditions. Underwater optical wireless communication (UOWC) is an emerging technology that offers high speed, low latency links over link distances in the order of metres. However, the effects of the UOWC channel present a challenge when designing a reliable link. These include: turbulence induced fading, which causes fluctuations in the received signal amplitude; particulate absorption, which causes an attenuation in the received optical power; and scattering, which causes spatial and temporal dispersion in the received signal. The SIM technique offers a resilience to turbulence compared to the state of the art on-off keying scheme, whilst additionally offering the potential for multi-level modulation orders – and therefore increased data rates – by encoding data on the signal phase as well as amplitude. In this work, PDM is used in conjunction with SIM to increase the spectral efficiency by separately modulating data across two orthogonal polarisation states. As long as these signals propagate identical channels, the polarisation states are maintained. Here, two orthogonally polarised laser beams are independently modulated with quadrature amplitude modulation (QAM), implemented via SIM to form the QAM-SIM-PDM technique. The performance of this technique is evaluated in terms of bit error rate and the maximum achievable data rate in clear, turbulent, and turbid water conditions. It is shown that data rates in excess of 10 Gbps are achievable using the QAM-SIM-PDM technique.

Toward supporting people's wayfinding activities, we propose a VLC-based guidance system for mobile users inside large buildings. A mesh cellular hybrid structure is chosen as the architecture, and the communication protocol is defined for a multi-level building scenario. The dynamic navigation system is made up of several transmitters (ceiling luminaries) that transmit map information and path messages for wayfinding. Each luminaire includes one of two types of controller: a "mesh" controller that communicates with other devices in its vicinity, effectively acting as a router for messages to other nodes in the network, or a "mesh/cellular" hybrid controller that communicates with the central manager via IP. Edge computing can be performed by these nodes, which act as border routers. Mobile optical receivers, using joint transmission, collect the data at high frame rates, extracts theirs location to perform positioning and, concomitantly, the transmitted data from each transmitter. Each luminaire, through VLC, reports its geographic position and specific information to the users, making it available for whatever use. A bidirectional communication process is carried out and the optimal path through the venue is determined. Results show that the system offers not only self-localization, but also inferred travel direction and the ability to interact with received information optimizing the route towards a static or dynamic destination. According to global results, the location of a mobile receiver is found in conjunction with data transmission. The dynamic LEDaided guidance system provides accurate route guidance, allows navigation, and keeps track of the route. Localization tasks are automatically rescheduled in crowded regions by the cooperative localization system, which provides guidance information and alerts the user to reschedule.

In this paper we demonstrate a LED-Laser hybrid transmitter to be used for colour-tunable, gigabit-per-second indoor visible light communication link. The hybrid transmitter consists of a white LED ring combined with a blue Laser diode incident on the diffuser surface which allows simultaneous control of the colour mixing and data communication performance. We explore colour tuning of the illumination light spot at the receiver by changing the transmitter lens position relative to the diffuser. We also demonstrate visible light communication at 1 Gbps data-rate using on-off modulated date for a link length of 2 meter. Due to beam spread from the diffusive surface, the hybrid transmitter also supports off-axis beam coverage across 40 cm diameter with bit-error rate below the forward-error correction (FEC) limit.

Increasing interest in indoor navigation has recently been generated by devices with wireless communication capabilities that enabled a wide range of applications and services. The rise of the Internet of Things (IoT) and the inherent end-to-end connectivity of billions of devices is very attractive for indoor localization and proximity detection. Other fields, such as, marketing and customer assistance, health services, asset management and tracking, can also benefit from indoor localization. Different techniques and wireless technologies have been proposed for indoor location, as the traditional Global Positioning System (GPS) has a very poor, unreliable performance in a closed space. The work presented in this research proposes the use of an indoor localization system based on Visible Light Communication (VLC) to support the navigation and operational tasks of Autonomous Guided Vehicles (AVG) in an automated warehouse. The research is mainly focused on the development of the navigation VLC system, transmission of control data information and decoding techniques. As part of the communication system, trichromatic white LEDs are used as emitters and a-SiC:H/a-Si:H based photodiodes with selective spectral sensitivity, are used as receivers. Through the modulation of the RGB LEDs, the downlink channel establishes an infrastructure-to-vehicle link (I2V) and provides position information to the vehicle. The decoding strategy is based on accurate calibration of the output signal. Characterization of the transmitters and receivers, description of the coding schemes and the use of different modulations will be the focus of discussion in this paper.

Optical and mobile broadband services have been widely adopted to support various applications including center-to-end and end-to-end communications. This raises further expectations for more and more natural and realistic communications by increasing network bandwidth and reducing latency. To support this evolution, 6G mobile is intended to increase the bandwidth to much over 10 Gbit/s and reducing the end-to-end latency to less than 1 ms. However, electrical processing is the key bottleneck to drastically increasing the bandwidth and reducing the latency in the current network architecture especially when the explosion of power consumption needs to be avoided. This paper discusses future optical network architectures and technologies to resolve the issue. In particular, it focuses on photonic networking to minimize the electrical processing across metro and access sections, and describes the technical challenges.

In this paper, we investigate asymmetric heterodyne downconversion, where dual-sideband (DSB) RoF signals are downconverted without experiencing the dispersive fading effects, which allows us higher conversion efficiency (higher RF link gain) and high tolerance against fiber nonlinearity, as well. Two methods for the downconversion are investigated and compared with each other, where dual sidebands allocated on (1) one side, and (2) both sides against the optical carrier frequency are asymmetrically downconverted into the intermediate frequencies and transferred as RF signals.

Data traffic is increasing explosively because of the development of various mobile applications and services for 5G and B5G communication. Optical intensity modulation has been used in optical access networks. However, due to the modulation bandwidth limitation of the optical modulator and the fiber dispersion, it is difficult to support the increasing data traffic only using optical intensity modulation. Therefore, multidimensional optical transmission using various optical resources has been researched. Modulation using optical polarization is widely studied as one of the multidimensional modulation resources because the system is simpler than other techniques. However, due to the squarelaw detection, which is an intensity-based signal reception, the signal needs to be received for each dimension respectively at the receivers, so the complexity of the optical receiver is increased as multiple resources are used. In this paper, we propose a single PD based signal receiving technique for the multidimensional signals modulated on optical intensity and optical polarization. The multidimensional optical signal is distorted by interdimensional interference. The proposed technique minimizes interference when receiving optical intensity and polarization modulated signals using a single PD. The proposed technique can separate each modulated signal for each modulation dimension of the multidimensional optical signals. We experimented the multidimensional signal detection using a single PD. We experimentally verified the BER performance of the QAM-PIRFSK signal transmission.

The performance of high-speed EML on sub-mount is discussed targeting 112 GBaud PAM4 modulations. The proposed sub-mount with high-speed EML demonstrates a high bandwidth of 80.4 GHz and a TDECQ value of 1.6 dB at 55 °C. The low TDECQ value of lower than 1.9 dB in a wide temperature range (20 °C - 70 °C) indicates that the proposed configuration is a promising candidate for 200G per lambda data center applications.

We released a novel Near-Packaged Optics (NPO) module for short reach interconnect using silicon photonics devices. The module has high-speed signal lanes up to 32 Gbps x 16 lanes with PCIe Gen 5 support. It also has a very small module size of 13 cm2 and a low power consumption of about 9 W. In addition, the module is compliance with Telcordia-GR-468-CORE. The electrical and optical interfaces are a board-to-board mezzanine connector and a multi-mode fiber array, respectively. By using multi-mode fibers, we were able to achieve error-free transmission up to 30 m and reduce mounting costs by passive alignment.

In this presentation, we will review the key optical and networking technologies which drove the evolution of Google's datacenter networks over the past 15 years. We then discuss critical directions for continued scaling in a post-Moore's Law paradigm.

Currently, most optical communication links shorter than ∼40 km employ intensity-modulation direct-detection (IMDD), and most longer links employ coherent. Demand for reduction in cost-per-transmitted-bit is relentlessly continuing, forcing IMDD and coherent to higher and higher rates. Coherent has better impairment equalization capability, better sensitivity, and a larger number of bits per transmitted symbol, ideal characteristics for next-generation links. However, coherent requires more complex lasers, more signal processing, more power consumption, and gear-boxing. IMDD, on the other hand, can be directly driven from electrical I/O and from electro-absorption-modulated lasers, making it significantly lower cost and power. We present taking one of the features of coherent, the use of dual polarization, and applying it in a blind way to IMDD. This allows a true and near-term way to continue on the cost-per-transmitted bit reduction path for optical data-center links.

A novel transmitter implementation, which will be capable of operating in both classical and quantum light regimes since it will be able to send single photons across a quantum channel and at the same time to serve as analog RoF transmitter currently deployed in X-haul topologies, is proposed. By spectrally isolating the sidebands of analog RoF signal and by controlling the EML’s modulation index, different mean photon numbers launched in one sideband can be obtained. We report on the architecture of our proposed transmitter station, and we demonstrate its operation through proof-of-concept experiments by performing successful RoF transmission links and by carrying out photon-counting measurements. The transmission of 200 Mbaud QPSK-modulated signal with acceptable EVM measurements of < 17.5%, as well the variation of the mean count rate of the filtered sideband as a function of the peak-to-peak driving voltage of radio signal at 28GHz were successfully performed, confirming that the sidebands of A-RoF transceivers can be used as single-photon carriers for quantum information.

Network densification is a crucial enabler for 5G, requiring the installation of a large number of devices and/or cables for the 5G transport network. This invited paper provides a techno-economic study focusing on adopting microwave and fiber equipment for 5G transport network deployments. Different architectures for low layer split supporting latency critical services are considered.

In future mobile networks, it is expected that more and more remote antenna units will be used, especially densely populated areas. To improve the ease of installation and operation of these remote antenna units with high availability, power-over-fiber technologies utilizing optical fibers have attracted much attention. In particular, this paper introduces power-over-fiber using double-clad fibers as a means of supplying electric power to drive a remote antenna unit. Double-clad fibers comprises a single-mode core and a much larger inner cladding core surrounded the single-mode core. This scheme enables us to provide not only broadband transmission into the single-mode core, but also high-power transmission into the inner cladding using a single optical fiber. In order to demonstrate the feasibility of this scheme, our group’s experimental demonstration of over 40-W electric power transmission with data signals is introduced. This paper also discusses the latest trends and future prospects of power-over-fiber technologies.

Digital avionics technology options to consider for fiber optics communication on future generation aerospace platforms encompass transmitters and receivers operating at 25 Gb/sec and higher data rates. A new round of device and packaging innovation and development will likely ensue as a stepping-stone based on prior work in the areas of single wavelength transmitter, receiver / transceiver and multi-wavelength optical subassembly development.

As data traffic in optical fiber network increases, there has been a lot of research that explores how to increase transmission capacity. Recent works suggest the multi-dimensional optical transmission as a novel solution. Multi-dimensional optical transmission is a signal transmission technique using orthogonal dimension sources such as intensity and phase of optical signal. However, previously proposed scheme has nonlinearity issue due to high frequency components in the modulation sequence and interference issue due to the transceiver structure. These issues limit the performance enhancement of multi-dimensional optical transmission. To overcome this limitation, geometric and probabilistic constellation shaping technique is aided to optical intensity-phase-polarization multidimensional modulation in direct detection system. We used quadrature amplitude modulation – differential phase shift keying – polarized intensity rotational frequency shift keying (QAM-DPSK-PIRFSK) modulation scheme to ensure orthogonality among optical intensity, phase and polarization. However, inter-dimensional interference (IDI) still occurs during direct phase detection using Mach-Zehnder delay interferometer (MZDI). To mitigate the IDI effect, RF-QAM signal modulated in optical intensity dimension is shaped geometrically and probabilistically. We used Hexagonal-QAM(HQAM) as a scheme of geometric constellation shaping to increase density of symbol and decrease peak symbol power. Also, probabilistic shaping is aided to HQAM model. With the mathematical analysis on IDI, symbol appearance probability is adjusted according to the intensity of the RF-QAM symbol. We verified the validity of the proposed technique with optical fiber transmission simulation.

DP-PAM8 modulated signals with probabilistic constellation shaping (PCS) are investigated for ultrahigh-data rates with diverse shaping strengths and DGD values using direct detection for short distances mainly seen in data centers. The investigation is conducted using numerical simulation, where system performance improvement is achieved when PCS is used. The probabilistic shaping mitigated the uncompensated DGD and dispersion effects in the transmission system. We found that the high-powered symbols close the eye causing high symbol error. Applying PCS opens the eye of the highpowered symbols but closes the eye for low-powered ones. Thus, optimization of the strength of shaping is necessary to get the best performance. Experiments were conducted to investigate the effect of probabilistic shaping on PAM8 system amplified using an optical semiconductor amplifier (SOA). A single polarization PAM8 case was only demonstrated due to accessibility limitations of required parts for dual-polarization PAM8.

The explosive growth of data-centric artificial intelligence applications calls for the next generation of optical interconnects for future hyperscale data centers and high-performance computing (HPC) systems. To unleash the full potential of dense wavelength-division multiplexing, we present the design and exploration of a novel transceiver architecture based on silicon photonic micro-resonators featuring a broadband Kerr frequency comb source and fabrication-robust (de-)interleaving structures. In contrast to the traditional single-bus architecture, our architecture de-interleaves the comb onto multiple buses before traversing separate banks of cascaded resonant modulators/filters, effectively doubling the channel spacing with each stage of de-interleaving. With a closed-form free spectral range (FSR) engineering technique guiding the micro-resonator design, the architecture is scalable toward hundreds of parallel channels—spanning much wider than the resonator FSRs—with minimal crosstalk penalty and thermal tuning overhead. This unique architecture, designed with co-packageability in mind, thus enables a multi-Tbps aggregated data rate with moderate per-channel data rates, paving the way for sub-pJ/b ultra-high-bandwidth chip-to-chip connectivity in future data centers and HPC systems.

Security enhancement is a major challenge in future 6G wireless networks. In this study, we have introduced a symmetric-key encryption system, which utilizes multilevel signaling, for the security of microwave signals against wireless interception. The system achieves quantum-noise signal masking at microwave frequencies via optical-tomicrowave frequency conversion based on the homodyne process, thus providing high signal security. We show experimental demonstrations of quantum-noise randomized phase-shift keying modulation/quadrature amplitude modulation cipher generation at a frequency of ~GHz via the intensity modulation/direct detection analog intermediate frequency over fiber transmission. The proposed system simultaneously achieves microwave signal delivery over a fiber link and signal encryption based on sufficient quantum-noise signal masking for wireless communication systems.

The ability of metamaterials to manipulate optical waves in the spatial and spectral domain has provided opportunities for image encoding. This combined with recent advances in hyperspectral imaging suggest exciting new opportunities for secure encryption. In this work, we propose a multi-channel scheme for secure image transmission across multiple wavelength channels. In contrast to conventional encryption schemes that perform a 1-to-1 transformation on a given plain image, we propose a 1-to-n transformation. We show that our scheme provides security against attacks of varying complexity provided a reasonable number of spectral channels is used.

This study demonstrates the optical fiber transmission of the Y-00 quantum stream cipher with quantum deliberate signal randomization (QDSR). QDSR is a deliberate signal randomization driven by a quantum random number generator, which substantially enhances signal masking using quantum noise to realize higher security. A 10-Gb/s line-rate dualpolarization phase-shift keying Y-00 cipher with QDSR is transmitted over a 400-km field-installed single-mode fiber link with optical amplifiers. When the phase levels after encryption and the index of QDSR are set to 2¹⁶ and 0.2, respectively, the quantum noise masking number increases by a factor of more than 40 compared to that without QDSR, which enhances security. However, the transmission penalty owing to QDSR remains small.

Conventionally, active alignment techniques are used in most photonics alignment applications. Active alignment techniques can require costly and sophisticated tooling system for high volume manufacturing. Besides, this technique is time consuming and sometimes gets very complex due to the photonic design complexity. A purely Passive photonic alignment technique is very useful in some application considering all the drawbacks of active alignment. Due to the advancement of wafer fabrication and mode converter designs, passive photonic alignment is now a possible solution. Here, we established a new technique to bond a 24-channel fiber array to a V-Groove photonic chip with simplicity and a more robust system. Industry standard insertion losses were achieved on multiple optical packages applying this technique.