A high-speed monolithic InP-based coherent photodetector PIC with a responsivity of 0.05 A/W at 1550 nm for polarization- and phase-diverse detection is demonstrated. The monolithic integrated polarization-rotator-splitter enables a polarization extinction ratio of > 15 dB over the entire C-band.

An optical-chaos secure communication of 86-Gb/s 16-ary QAM signal over 100-km fiber transmission is experimentally demonstrated under the 20%-overhead SD-FEC BER threshold of 2.0×10-2 by using wideband chaos synchronization of discrete-mode semiconductor lasers.

We demonstrate transmission of 383 WDMx55 SDMx24.5 GBd 16-QAM signals spanning Cand L-bands over 12.5 km 55 mode fiber. The resulting data rate of 3.56 Pb/s more than doubles the previous record data rate in optical fibers with standard cladding diameter.

A many-to-one mapping geometric constellation shaping scheme is proposed with a fixed modulation format, fixed FEC engine and rate adaptation with an arbitrarily small step. An autoencoder is used to optimize the labelings and constellation points' positions.

We reported a high-performance 2ch EML array on a wide bandwidth sub-mount: Capable of dual high-speed modulation, demonstrating 3 dB bandwidths of > 67 GHz and low TDECQ values of ≤.1.75 dB for 112 GBaud PAM4.

We demonstrate a 224-GBaud CSRZ-OTDM optical transmitter achieving net bit rates of 2.59 Tb/s/λ back-to-back and 2.52 Tb/s/λ after 80-km SSMF transmission. An 8×4 digital calibrator effectively compensates for spurious distortions.

Long-haul transmission of 40-Gbaud PDM-QPSK signals over 7280-km coupled 4-core fibers is demonstrated with entire 5/4× oversampling DSP including a frequency-domain adaptive 8×8 MIMO filter. The 5/4× oversampling DSP reduces the computational complexity by 34% compared with the conventional 2× oversampling DSP with negligible penalty.

We demonstrate a transparent in-line optical power monitor using an InP-based phototransistor monolithically integrated with an InP/Si hybrid MOS optical phase shifter. The trap-mediated photodetection and amplification by phototransistor enables photodetection down to -44 dBm with an optical insertion loss of <0.25 dB.

We present a 3.5 mm × 2.0 mm compact single wavelength laser optical sub-assembly with a Si photonics-based wavelength locker chip. The measurement results showed a good agreement with the designed spectrum and 8-GHz bandwidth of target slope > 0.027 GHz^-1were successfully obtained.

Multiband transmission is the most promising candidate for increasing transmission capacity in fiber optical communication systems in the near–term. Challenges for introducing this technology and solutions for overcoming them are detailed with a focus on transmission performance, system installation, amplifier manufacturing and device control.

We evaluated a transmission system with 28 Gsps digital-down-conversion and pre-emphasised intermediate-frequency-over-fibre. The system accommodated four OFDM-16QAM signals of 1.5 GHz bandwidth. For OFDM-64QAM, the EVM was only 0.6% short. An ADC which has an ENOB of 6 enables the system to transmit OFDM-64QAM.

We demonstrate a hybrid integration combining InP-based and Si-based PICs with a low-loss butt-coupling of 1.7 dB/facet. Mach-Zehnder modulators with the 3-dB-bandwidth of 85 GHz, a PBS and rotator, VOAs, and MPDs are successfully integrated in the ultra-compact size of 2.7 mm × 6.8 mm.

We propose a modified low-complexity architecture for hierarchical distribution matching (DM), achieving 2²²-ary quadrature amplitude modulation or 4.32-Tb/s data rate on a field programmable gate array with a limited rate loss. Such a performance-complexity balanced DM helps minimizing the power consumption with probabilistic shaping.

We demonstrate a standard cladding 4-core fiber with highest figure-of-merit by optimizing its design of effective area, loss and crosstalk characteristics simultaneously for submarine transmission. The 10,140km transmission with spectral efficiency of 7.52bit/s/Hz is achieved with counter-propagation configuration among neighbouring cores.

A submarine spatial-division-multiplexing branching unit (BU) prototype supporting four core fibers (4-CFs) is demonstrated. The BU prototype comprises three integrated 4-CF all-port horizontally flipped splitters and three integrated 4-CF core selective switches to form the core-by-core branching functionality.

This paper discusses the deployment of End-to-End packet-optical connectivity services over an edgecloud continuum, considering the importance of location awareness. It proposes architecture, data models, and placement algorithms for provisioning and updating these services in the ADRENALINE Testbed using the ETSI TeraFlowSDN controller.

A closed-form expression that estimates the nonlinear interference of arbitrary modulation formats in Raman amplified links is presented. Accounting for any pumping schemes and inter-channel stimulated Raman scattering effect, the formula is applied to an optical bandwidth of 20 THz and validated using numerical simulations.

We propose a simple method to calculate LLR for IM-DD system with MLSE and SD-FEC. We show that an advanced MLSE with the simple calculation method which shapes the LLR distribution makes NGMI higher for 128-Gbaud PAM4 signal in a severe bandwidth limitation.

We discuss performance and implementation aspects of geometric and probabilistic constellation shaping. We demonstrate how rate adaptivity of PS has made it a very powerful tool for optical communications industry regardless of its higher implementation complexity.

We present the first demonstration of a silicon ring resonator, coupling-modulation-based, dual-polarization I/Q modulator in an optical sub-assembly with integrated SiGe drivers. We demonstrate 78-km 802.6 Gbps transmission with 90-GBaud PS-64-QAM modulation.

Record 400-Gb/s/lane net-rate (155-GBd PAM-8) IM-DD signals are transmitted in the O-band over installed 10-km 4-core fibre using in-house broadband InP-DHBT amplifier and our nonlinear-MLSE, achieving a 1.6-Tb/s total capacity for future data-centre Ethernet networks.

By employing single-mode power-feeding over a four-core fibre with a standard 125-μm cladding diameter, power-over-fibre with 1 W class and over 10 km-long was demonstrated for the first time. Over 10 Gbit/s self-power-feeding bi-directional data communication in the single 4-core fibre is also demonstrated.

We demonstrate a silicon-photonics 16×16 Clements-type vector-matrix multiplier, performing MNIST classification. The imperfection in the largest-scale photonic analog circuit was corrected using our proposed novel machine learning-based tuning method with a high fidelity of 0.904, significantly improving the experimental MNIST classification accuracy.

Two-dimensional linear optical sampling is presented for observing ultrafast spatiotemporal complex signals. By directly observing complex cross-sectional images, the technique is useful for spatial modes of multimode/multicore fibres. The intramodal delay differences in step-index and graded-index fibres are analysed with a ps-level time resolution.

We demonstrate net 500-Gbps (64-Gbps/channel, BER<1E-6) and ~840-Gbps (112-Gbps/channel, BER<3.8E-3) SDM-Tx over 2-km of standard-cladding-diameter 8-core fibre with <pJ/bit energies based on 8-channel O-band membrane DML-array-on-Si and direct chip-to-multicore-fibre fanin. Simultaneous operation confirmed negligible optical and electrical crosstalk.

To satisfy stringent requirements of low- and stable-latency applications, we propose a real-time cooperation scheme of optical network and computing resource controls. Experimental results demonstrated automatic path and resource switching can be performed within 63 milliseconds as a result of the novel cross-domain analysis function.

Sixteen-channel DML array integrated with spot-size converters are fabricated on a SiO₂/Si substrate with a footprint of 1.11 × 2.75 mm², demonstrating 28- and 56-GBaud PAM4 operations and BERs below the KP4-FEC limit after 2-km transmission.

We propose a novel timing recovery algorithm for digital multi-band systems. 320-Gbit/s experiments show that the proposed algorithm is robust to spectral roll-off, dispersion and DGD and outperforms the double-period algorithm under large clock frequency offsets and loop delays.

We demonstrated transceiver calibration for 96-GBaud PM-64QAM via constrained adaptive multi-layer filters using weak Tx nonlinearity over 120 km SMF. By separating Tx/Rx frequency-dependent distortion, we showed flat Tx signal spectrum and 48 % reduction of 2x2 MIMO filter tap, compared to the conventional calibration.

Using a high-slope-efficiency broadband modulator with theoretically-predicted merit, we demonstrated 900mV_pp-driving, 384Gb/s PAM8 over 300m SMF in C-band with no Tx DSP, Rx-side symbol-spaced 41-feedforward & 1-feedback-tap DFE, and hard-decision FEC. No optical or RF amplification was used for reception.

We designed a digital coherent continuous variable quantum key distribution system achieving higher spectral efficiency by extracting timing information from a polarization-multiplexed QPSK reference signal and demonstrated the feasibility of distributing a secret key over a 100 km SMF link.

We successfully demonstrate the extension of service coverage for PON system through the use of combo PON repeater. Transmission distance of 55 km and 128-way split is achieved and stable operation of packet throughput of 8 Gbps in both directions over 72 hours is verified.

We developed a technique to identify fibre type based on power profile estimation using coherent receivers. With the proposed method, SSMF and NZ-DSF were successfully identified in 96GBd DP-16QAM signal, 9-span transmission testbed.

We report significant noise reduction in distributed acoustic sensing (DAS) link using enhanced-scatter fibre (ESF). The longest reach of 195km DAS link without inline amplifications is also demonstrated. We further present demonstration of simultaneous fibre-optic sensing and 400Gb/s data transmissions over 195km fibre using ESF.

We demonstrate full-duplex analogue transmission of mm-wave radio at 29.3/34.3GHz using an EML to simultaneously perform coherent downlink detection and uplink transmission at the RRH. We further introduce photonic down-conversion of the uplink to simplify its frequency translation while eliminating dispersion-induced fading over 15km reach.

We compare hardware parallelization of CD equalizers on 10 km 4x200 Gb/s IM/DD PAM4 O-band measurements. A single neural network equalizer with multiple output symbols saves 20% of reference chip area versus multiple single-symbol output variants and 77% versus Volterra non-linear equalizers. Multi-task learning enables cost-efficient scenario flexibility.

A novel connection structure for multicore fibre (MCF) is proposed to enhance the uniformity of optical properties among cores in MCF links by utilising the natures of polarity and rotation while maintaining core number identification.

We propose mixed-precision integer-arithmetic-only NNs for low-complexity equalization in a 50-Gb/s 25-km DML-based PAM4 IM/DD link based on input neuron partitioning. The proposed scheme avoids floating-point weight operations and saves 26.3% memory at a minimum NN size compared with fixed-precision quantization counterpart without degrading BER.

50G-PON upstream burst mode requires training patterns to help both the digital signal processing convergence and the clock recovery. We evaluate the performances of 6 training patterns and conclude that the 32-bit long pattern is the best compromise between clock recovery and DSP convergence.

We fabricate a double cladding 7-core EDF with hexagonal cladding and apply to claddingpumped 7-core EDFAs. We confirm output power increase of 1.3 dB and 2.4 dB in C-band and L-band amplification, respectively, by cladding shape change from circular to hexagonal cladding.

We demonstrated a high-data rate mobile-FSO communications up to 20 Gbps assuming 10-20 m short distance communication using a newly developed multi-stacked large PIN-PD and a compact transceiver including the beam tracking system.

We revealed for the first time that the wavelength characteristics of spatial mode dispersion (SMD) can be effectively flattened by implementing 4-, 8-, and 12-core randomly-coupled multi-core fibres in high-density cables. Sufficiently low and stable SMD properties were confirmed independent of the number of cores.

We describe a 2 Gbaud 256 QAM coherently-linked optical and wireless transmission at 28 GHz with an injection-locked carrier-frequency converter and small microstrip antennas. With this combination, 16 Gbit/s data were successfully transmitted over a 10 km SMF and 10 m wirelessly.

We validated <1-dB-mean-absolute GN-model-based SNR estimation errors against experimentally measured SNRs in 15.2-THz ultra-wideband transmission over 160- and 400-km G.652.D fibre consisting of 80-km spans with PPLN-based optical parametric inline amplifiers. We found gain equalization for increasing the total throughput using SNR estimation.

We demonstrate forward-pumped distributed Raman amplification in C and L bands using semiconductor wideband incoherent optical sources as first-order pumps including newly developed incoherent optical sources for L band amplification. We confirm flat on-off gain and low relative intensity noise of transmitted signals.

We propose a low-complexity, fast-converging frequency-domain MIMO equaliser for mode-dependent-loss-impaired long-haul space-division-multiplexed transmission. An introduction of recursive-least-squares method performing computations only within signal bandwidth accelerates MIMO equaliser filter learning, achieving a world's-longest 10-spatial-mode transmission over 1560 km, while mitigating computational complexity requirement by 40%.

We demonstrate a C-band cladding-pumped 12-core erbium-doped fibre (EDF) amplifier with less than 40% electrical power consumption compared to conventional amplifiers enabled by our proposed cladding-tapered pump launching scheme. The highest power conversion efficiency of 14.5% was achieved by applying our pumping reflection technique.

We propose a C+L-band lumped repeater with over-15-dB-gain PPLN-based optical phase conjugators and EDFAs to mitigate gain saturation in parametric amplification. The proposed repeater achieves ~7-dB NF and uniformizes the SNR variation of 84-channel 640-Gbps signals within 1 dB after 1120-km G.652.D fibre transmission.

Optical quantum computers, which use traveling waves of light, are highly compatible with optical telecommunication technology and are capable of large-scale and high-speed computations. We have established a fundamental technology for generating Gottesman-Kitaev-Preskill qubits, which are non-Gaussian states and essential for realizing fault-tolerant quantum computers.

We proposed a method of digital pre-distortion scheme for transmitters with electrically analogmultiplexed digital-to-analog converters (DACs), based on a digital inverse multiplexing model. We performed 132 Gbaud PCS-64QAM signal generation and detection with an > 3.7-dB signal-to-noise ratio and > 180 Gb/s net bitrate improvement.

We propose a bandwidth-partitioned spectral inversion (BPSI) technique to mitigate intercore-crosstalk impact over multi-band MCF transmission. A decreased wavelength-dependent crosstalk difference was experimentally achieved over four-core MCF below 1 dB even using C+L band by PPLN-based BPSI, negligible OSNR-penalty variation in 96-Gbaud PCS64QAM signal transmission.

We report the transmission of a coherent 400-Gbps dual-polarization (DP) 16QAM channel that transport QKD-secured 100-GbE data stream with other fifty-four WDM channels at 100 Gbps over 184 km of SSMF through three QKD links and two trusted nodes.

An arc-shaped anti-resonant hollow-core fibre (AR-HCF) is fabricated with the outmost AR layer removed, reducing the microstructure diameter by 16%. A loss level below 0.5 dB/km from 1220 nm to 1340 nm and a minimum loss of 0.28 dB/km±0.1 dB/km @ 1290 nm has been achieved.

Optical side leakage radiometric measurement is implemented on anti-resonant hollow-core fibers. The metrics of propagation loss, defect location, and phase birefringence are acquired with high precision. Polarization-dependent light leakage collected by an integrating sphere is identified.

This paper reviews the latest effort in both ITU-T and IEEE on the next generation optical access networks. It discusses progress in projects G.suppl.VHSP, G.9806, and 802.3dk. Related standardization endeavours in exploring new applications of optical access systems are also covered.

A self-supervised learning scheme is proposed for neural-network-based perturbative fiber nonlinearity compensation with a designed proxy task by using phase-conjugated unknown sequences. The self-supervised trained model can be applied directly to the corresponding dual-polarization system with no obvious performance penalty compared with the supervised one.

Full C+L-band transmission is experimentally demonstrated using multivendor 4-core fibre cables installed in an outdoor environment. By applying bidirectional transmission technology to suppress core-to-core XT, the transmission distance can be extended to 2,160 km, which is 1.5 times longer than that for unidirectional transmission.

Long-haul transmission over 3520 km in a 4.725-THz WDM configuration with 225-GHzspacing in the C-band has been successfully demonstrated with a high-symbol-rate 200-GBd polarization-division-multiplexed QPSK signal, which was generated using in-house >110-GHz analogue multiplexers and >130-GHz-bandwidth electrical amplifiers based on ultra-broadband indium phosphide technologies.

We propose and demonstrate an end-to-end intelligent constellation optimization scheme in PS-QAM-based FLCS-CPON under user-specific access conditions. With deep-learning-based autoencoder for transmitter, channel, and receiver, results show 3.7-dB power-budget improvement and 6.1-dB dynamic-range enhancement for PS-32-QAM FLCS-CPON with 250-Gbps peak line-rate after 50-km SMF.

We demonstrated under six minutes automatic provisioning of optical paths over fielddeployed alien access links and WDM carrier links using commercial-grade ROADMs, whitebox muxponders, and multi-vendor transceivers. With channel probing, transfer learning, and Gaussian noise model, we achieved an estimation error (Q-factor) below 0.7 dB.

We develop highly sensitive and accurate multi-frequency Φ-OTDR distributed acoustic sensing suitable for measuring large-scale vibrations over sub-μεamplitudes. We capture more correct detailed vibration patterns on both underground and aerial sections of an optical fibre network deployed for telecommunication services in a real-field trial.

We evaluated 144-GBaud 64QAM signal characteristics with transmitter-side SOA. Back-toback experiments demonstrated up to 1.38-Tb/s/λ net bitrate with optimized SOA input powers and injection currents. We also performed 80-km SMF transmission between 1530.529 and 1564.067 nm, achieving >1.3-Tb/s/λ net bitrate with the optimum SOA conditions.

An L-band 4.1-THz 7-core signal has been successfully amplified by using recycled pump light from C-band 4.6-THz 7-core cladding-pumped multicore EDFA. 4.8 % of power conversion efficiency with a single pump laser diode for C+L-band cladding-pumping was obtained twice large as for C-band.

We experimentally investigate mode permutation schemes to mitigate the impact of differential mode delay in a long-haul 15-mode fiber l ink. These schemes reduce the rate at which the link intensity impulse response duration increases with transmission distance, which results in a decreased MIMO DSP complexity.

We present a series of experiments testing a closed-form ultra-wide-band EGN model, carried out over a 5-span full C+L transmission line. Transmission ranged from quasi-linear to deeply non-linear with significant ISRS. We found quite good correspondence between predicted and measured performance.

An optical isolator with 5.5-mm outer diameter and 29-mm length was fabricated using uncoupled 4-core fiber. Low inter-core crosstalk of -50 dB was obtained in the wavelength range from 1525 to 1570 nm and validated in the temperature range from -5 to +70°C.

We propose a quasi mode scrambler to mitigate exaggerated MDL accumulation specific to recirculating loop systems. We measured accumulated MDL in a recirculating loop system using coupled-core multicore fibres and mode scrambler. Unlike PDL in uncoupled-core multicore fibres, accumulated MDL was not reduced by scrambling.

Channel-polarized multilevel coding (CP-MLC) improves the net coding gain of the concatenated codes by 0.07 to 0.20 dB under short-block soft-decision FEC and KP4 codes while simultaneously reducing the complexity by 37.5% or more.

We experimentally demonstrate fiber-longitudinal monitoring that visualizes polarization-wise signal powers. The method is based on linear least squares and successfully estimates the position and amount of PDL in a multi-span optical link. Results show accurate PDL estimation with errors below 0.5 dB at 1-km granularity.

We propose the application of an SD-FEC technique to an eigenvalue-modulated signal using a multilabel neural-network demodulator. The experimental results indicate a successful operation with an error-free transmission through a 3000-km optical fiber line.

This paper presents latency and jitter results of cascaded regular Passive Optical Network to serve consecutively access and several rooms in the office. We also consider the impact of the wavelength and optical power of an alien Point to Point source on PON transmission.

We propose an end-to-end EDFA gain model using denoising CNN. Our proposed model achieves state-of-the-art performance on both the same device used for training and different physical units of the same make, with the lowest RMSEs compared to conventional CNN and previously-reported NN schemes.

We demonstrate optical amplifier-free transmission over 2 km with 100-GBaud PAM-4 using a spot-size-converter-integrated directly modulated membrane laser on a SiC substrate. The spot-size converter using a SiOx waveguide is fabricated by partial removal of SiC, resulting in fibre-coupling loss of 2.7 dB.

We propose an extended metro/access integrated network architecture comprising two layers with fiber-based and wavelength-based cross-connects for fiber-path and end-to-end wavelength connection services, respectively. Simultaneous demonstration of 100-Gbit/s dense wavelength-division-multiplexing transmission and field-access fiber sensing without interference confirms its effectiveness.

We demonstrate recirculating loop transmission of 4 × 518 × 24.5 GBd DP-QPSK signals spanning the S, C, and L-band over 12 345 km of 4-core fiber. T he t hroughput o f 138.9 T b/s results in the highest data-rate-distance product measured in any standard cladding diameter optical fiber.

By employing successive interference cancellation decoder and redundant receive channels, we achieved a record-high line rate of 689 Gbit/s, channel number of 10, and net spectral efficiency of 13.9 bit/s/Hz in single-wavelength mode-division multiplexing free-space optical transmission under strong turbulence.

A reconfigurable, technology-agnostic X-haul optical infrastructure with active wavelength routing for converged A-RoF/D-Band, D-RoF/E-Band and SDoF streams was demonstrated. The deployed SDN-enabled AWGR-based transport topology supported real-world services including HD video and mobile traffic.

We propose subcarrier grouping to simplify the entropy loading for OFDMA, where each user only treats one probabilistic-shaping format. We reveal a diversity gain of OFDMA for the first time over the rate-adaptive TDM in a 400G-class point-to-multipoint IM-DD system.

We review various use cases of distributed-fiber-optic-sensing and machine-learning technologies that offer advantages to telecom operators' fiber networks on existing fiber infrastructures. By leveraging an edge-AI platform, perimeter intrusion detection and implosive acoustic event detection can be performed on-the-fly, ensuring real-time detection with low latency.

We demonstrate a 1.6-Tb/s coherent transmission based on a fully packaged 80-GHz-class coherent driver modulation (CDM) compatible with OIF HB-CDM implementation agreement, indicating a practical single-channel 1.6-Tb/s solution is around the corner.

A cost-effective and spectrally efficient system for the transparent transmission of radio signals using full-optical FSO transceivers and a common optical carrier is proposed. Simultaneous transmission of 28-GHz 5G new radio standard-compliant and 88 Gb/s 286-GHz sub-terahertz signals is successfully demonstrated over a converged fiber-FSO-radio system.

We demonstrated add-drop Si microring resonator switch using InGaAsP/Si hybrid MOS optical phase shifter. Through careful Si waveguide design, quasi-single-mode add-drop operation with bipolar phase tuning was achieved. Owing to negligible gate leakage current, high extinction ratio of 34 dB was obtained with150 fW.

To deal with the excessive transport capacity and power consumption challenges faced by Cell-free massive MIMO systems, we propose a fronthauling solution with MIMO-cluster-aware schedulable coherent digital subcarriers. The system power consumption is modelled, and simulation results show significant power saving compared to P2P optics.

We fabricate a polarization-independent electro-optic Silicon-Photonic circuit that monolithi-cally integrates Mach-Zehnder interferometer switches and filters for creating a fast and high-port-count optical switch. Design integrity of the switch is verified by 3,712×3,712 switch experiments using 128-Gb/s DP-QPSK signals; switching times are under 55 nanoseconds.

We demonstrate PON slicing for fronthaul, business, and residential services coexisting in a single ODN , ensuring independent slice performance, and resource allocation by slice-aware DBA. The latency of fronthaul slice is less than 200 μs using Co-DBA/CTI.

We report using digital holography for characterising optical fibre tapers. In a 6LP Few Mode Fibre, MDL increases from ~1.8dB to ~16.1dB for a 2 mm transition length when taper diameter is reduced from 125 μm to 25 μm.

An SOA and switch enable the bypass of a PtP OLT to obtain reconfigurable (via AMCC) multirate 25 Gbit/s NRZ or 50 Gbit/s PAM4 bidirectional real time transmission and extended reach up to 40 km (80 km total reach).

We realize a Burst Mode (BM) transmission at 25 Gbps in a Passive Optical Network (PON), using a BM-TIA prototype. The sensitivity of -24.8 dBm B2B and -21.9dBm after 20km SMF is experimentally demonstrated in real-time in burst mode with a Directly Modulated Laser (DML).

Quantum fluctuations fundamentally affect optical signal regeneration and detection. This results in ultimate quantum limits on the performance of optical communication links and enables innovative physical layer security solutions such as quantum key distribution.

We propose and experimentally demonstrate a model-based deep-learning framework that optimizes fiber-terahertz communication system end-to-end, while retaining the conventional single-car-rier transceiver architecture. Jointly learning of pulse shaping, pre-equalization, digital pre-distortion, and transceivers achieves a 1.8-dB sensitivity gain and 4-Gb/s capacity improvement at 209-GHz fiber-THz system.

We demonstrated a real-time high sensitivity 15Gbps 4PPM-QPSK receiver based on a single FPGA chip. An efficient PPM symbol synchronization scheme has been realized. In the real-time experiment, the receiver achieved a sensitivity of -48dBm at BER of 1E-3.

We demonstrate a largest ever port- and channel-count monolithically integrated wavelength cross-connect switch using 256 FSR-free grating-assisted contra-directional couplers and 1,024 thermo-optic Mach-Zehnder switches. The fabricated chip was fully packaged and controlled to measure spectra of representative switching states for all the 16 wavelength channels.

We investigate core pitch dependence of the power coupling coefficient and which multi-core fiber (MCF) layout is best for achieving the highest capacity. We demonstrate that 22-core MCFs with 7-concentric circular structures can accommodate approximately 175% higher traffic loads than irregular hexagonal 27-core MCFs.

By exploiting multiple longitudinal modes of a free-running Fabry-Pérot laser, we achieve a record aggerated data rate of 1 Tbit/s in the C-band over 1 km. The BER below the HD-FEC level for ten modes is obtained with a T-spaced FFE.

This paper reports the first experimental demonstration of 4×130 Gbit/s probabilistically shaped PAM-16 transmission over 1km using an integrated SOA-PIN design for next-generation intra-DCIs. With a T-spaced neural network equalizer, a BER below the SD-FEC threshold is achieved under a 20-GHz bandwidth limit.

We experimentally evaluate the impact of link failure on existing services with different design strategies in a commercial equipment-based meshed network. SNR-based power equalization yields 0.7 dB SNR margin improvement; a max 1 dB SNR penalty-reduction compared with blind scenario is achieved by parameters refinement.

We propose a novel solution to mitigate FWM interference using link segmentation by slightly shifting the dispersion zero. 2 and 10 km links with 1.6 Tb/s data-rates were simulated using eight O-band channels carrying 112 Gbd PAM-4 signals. A comparison with polarization interleaving is done.

We assess different bandwidth loading strategies in an unrepeatered system and measure the non-linear noise contribution of ASE-based or modulated interferers vs their spacing to the channel under test. We then compare our results to the AWGN theory

A Bayesian optimization-based approach was investigated with data extracted from a live network as part of a field trial to retrieve hard-to-measure equipment parameters. These parameters were then utilized to improve the accuracy of the Quality of Transmission estimation.

We demonstrate C+L-band optical-frequency-comb regeneration from seed-signals that can be split, amplified, and transmitted over a novel metro/DC network architecture. Multi-core-fiber seed and data distribution with spatial-switching enables identical network-wide transceiver combs and ≈100 Tb/s/core and 600 Tb/s per-fiber data-rates.

This paper reviews recent advances in the development and application of silicon core fibres for nonlinear photonics. Particular focus will be placed on novel device designs that benefit from the fibre geometry and integration with existing components.

We summarise switching strategies for high-capacity networks based on space-division multiplexing (SDM) fibers, including multi-mode fibers and both strongly and weakly coupled multi-corefibers, and summarise some recent experiments in each fiber type.

The integration of QKD technology for 6G deployments facilitates advanced protection against attacks on critical infrastructures. We detail, implement and demonstrate the Key Management and Control Layer operations of a Free Space Optics-based QKD link for network access including key delivery with QoS guarantees.

We successfully demonstrate 10 & 20 GBaud QPSK and 5 & 10 GBaud 16QAM after 1 km transmission using incoherent spectrally sliced ASE as a light source and a self-homodyne detection receiver.

We experimentally demonstrate an instantaneous frequency measurement system based on a microwave photonic filter with linear amplitude responses (positive and negative slope). The overall rms error is 42.2 MHz in the range 2-20 GHz.

An O-band photonic integrated 4×4 SOA-based space switch based on the broadcast and select architecture has been designed and fabricated. Experimental validation shows error-free operation with a power penalty of < 0.5 dB, an on/off ratio of 40 dB and an OSNR of 50 dB.

We show combined soft-failure detection, identification und localization enabled by machine learning using experimentally obtained optical spectra as inputs. Our VAE and GAN-based framework shows high F1-scores requiring only 6% of total training data while being able to identify unknown failure spectra with 99.81% accuracy.

We report a 1.5 μm InGaAlAs/InP DFB laser integrated with high power SOA, which emits 205 mW light power at 20 °C. The SOA is used for NRZ data modulation at up to 25 Gb/s. Clearly opened eyes and BER below 10E-10 can be obtained.

Through a novel design method for test signals, we revive a convenient nonlinear distortion characterization method that has been impractical for 50 years for optical communications. An 0.1 dB accuracy is achieved using a spectrum analyzer only.

We proposed a low-insertion-loss and non-volatile optical intensity modulator based on Ge₂Sb₂Te₃S₂(GSTS), a recently proposed widegap phase change material. We demonstrated matrix-vector multiplication using a new photonic tensor core with GSTS intensity modulators, enabling a high recognition accuracy of 97.34 % in CNN.

A transit-time-enhanced silicon photodetector is proposed and fabricated in standard CMOS without process modification. By adopting the lateral interleaved junction, this PD features a 0.13-A/W responsivity and a doubled 10.43-GHz transient-time bandwidth. Moreover, a clear 10-Gb/s 850-nm optical eye diagram is observed.

We propose a decode-and-forward (DF) physical-layer network coding (PNC) scheme based on residual field of algebraic integers for OFDM-VLC two-way relay networks. Experiments with up to 1.47-Gbit/s throughput show that the proposed scheme enables DF-PNC of high-order QAM and significantly outperforms the conventional amplify-and-forward scheme.

Solid silica fibre has fuelled telecommunications for ~45 years. The development of hollow core fibre offers a radical alternative, creating an opportunity to refine networks further. We consider the practicalities of scale deployment and consider the use in the access network.

We propose an online paradigm to simultaneously model and optimize Raman gain profiles. Real-time experiments demonstrate the proposed scheme can approach the optimal modelling and optimization performance within 30 data, reducing ~90% of the data compared with the scheme based on an offline-built model.

We present an investigation into direct butt-coupled interconnection of hollow-core fibres to single-mode VCSELs operating at 850 nm. Our results show the coupling efficiency can be significantly improved from 10% to 69% using a graded-index fibre (GIF) based, all-fibre mode field diameter (MFD) converter.

An overview is given of our short-reach OWC system concept and key techniques for remote steering of multiple narrow beams, accurate calibration-free user localization, and scalable wide field-of-view receivers. Bidirectional communication of GbE high-definition video services is demonstrated including interfacing to common user laptop equipment.

Optical networks aim at improved capacity and cost efficient data transport solutions. Resulting emerging technologies, such as multi-wavelength transponders with increased rate-adaptivity and multi-band systems, significantly complicate the planning. We provide strategic insights for upgrades from a long-haul optical transport network operator's perspective.

High power generation is an enabling technology for high capacity free space optical feeder links. We show the feasibility of optical transmission of WDM OOK / DPSK at high power based on 50 W amplifiers and their coherent combination to deliver up to 97 W power.

We present a novel fibre-optic transmission system based on the phase modulation via nonlinear Fourier transform for finite-genus signals with no periodicity constraint, which is achieved through designing a neural network-based receiver and demonstrate, as a proof of concept, signalling below 7% HD-FEC BER threshold.

A summary of the network architecture that adopts flexible path bundling and bundled path routing is provided in this paper. This architecture can also support spatial division multiplexing and multi-band transmission. Numerical simulations and transmission experiments confirm its validity.

We review recent Tbit/s class optical free space transmission experiments.

We propose and experimentally demonstrate an FTN signal processing scheme based on low-complexity nonlinear M-BCJR equalization with DNN model for nonlinear channel fitting in IM/DD system, achieving 140-GBaud PAM-8 signal transmission over 0.5-km SSMF in the C-band and a net-data-rate of 340 Gbps/λ.

We demonstrate a simplified, coherent W-band fiber-mmW integrated system with an envelope-detector at user-end for complex-signal detection, enabled by the adaptive KK algorithm. Over 3.5-dB sensitivity improvement with 60-Gbps 16-QAM signal through 20-km SSMF and 1-m 94-GHz wireless is achieved at the 3.8E-3 BER threshold.

The first real-time demonstration, including FEC and client traffic, of point-to-multipoint transmission over a single fiber passive optical network with two pluggable 100G Leaf modules communicating with a single 200G Hub module is presented.

We propose multi-channel power profile estimation considering both XPM and SPM. We achieve improved estimation accuracy by applying multi-bandpass filter and can effectively alleviate the impact of misalignment of waveforms combined in MC-PPE by minimizing the mean-square-error through off-line processing in digital domain.

In this paper we present the integration of a low-cost QKD system into a low-loss, asymmetrical beam steering platform including a polarisation calibration unit. Initial results are presented demonstrating a secret key rate of 400 bit/s for the overall system.

We investigate the performance of S-band transmission over a G.654.E optical fiber with cable cutoff up to 1520 nm. Modeling of higher order mode attenuation and MPI generation in representative cable deployment bend conditions demonstrates negligible impairment from MPI in realistic conditions.

We demonstrate the operation of an end-to-end 5G network enabled by bandwidth efficient and low latency transport of mobile fronthaul traffic over a 25GS TDM-PON system using cooperative transport interface (CTI) and Cooperative DBA (Co-DBA).

We demonstrate free-space Y-00 cipher transmission in artificial dense fog with a high attenuation of 20 dB. The Y-00 cipher carrying 1.5 Gb/s IM and 10 Gb/s DP BPSK signals are securely transmitted in such a harsh condition where the FSO receiver is invisible from the transmitter.

We propose a practical and generalizable PNPAConv-based neural structure to adapt network-scale QoT estimation. The performance log₁₀MSE achieves -1.982 and -1.506 over JPN12 and EURO28, respectively.

We study the techno-economics of hollow core fibers (HCF) for submarine cable applications. The potential value of HCF is given in terms of maximum allowable fiber cost multiple relative to solid core fiber resulting in system cost/bit parity for different system and HCF characteristics.

We propose and compare two DSP anomaly detection schemes based on state of polarization monitoring over 35-km of installed metropolitan fibers. We experimentally evaluate their statistical performance through receiver operating characteristics curves analysis.

We report silicon photonic integrated circuit-based coherent terahertz signal generation and signal distortion recovery performance for transmission capacity expansion and reliable mass production. The experimental results demonstrate 16QAM optical signal transmission up to 100 Gbps and error-free 1-m terahertz wireless transmission up to 50 Gbps.

We optimize nonlinear Digital Pre-Distorters for VCSEL-MMF links using an End-to-end (E2E) learning architecture focused on TDECQ IEEE specifications for 100 Gbps/λ[1]. We experimentally demonstrate that our E2E training improves the TDECQ performance by more than 0.8 dB compared to Direct Learning.

We report the first coexistence experiment of 1550 nm single-mode squeezed light with a 1310 nm classical light over a 10 km fiber channel, using a locally generated local oscillator. Using real-time phase locking, we measure up to 0.5 dB of squeezing.

We demonstrate the digital twin of a network, network elements, and operating environment using machine learning. We achieve network card failure localization and remote collaboration over 86 km of fiber using augmented reality

We demonstrate a direct-detection phase retrieval receiver based on silicon photonics. The receiver implements strong dispersion and delay lines on a compact chip. We retrieve the full field of a 30-GBd QPSK signal without a carrier or local oscillator.

The paper discusses strategies for achieving low-complexity neural network-based equalizers for optical communications, addressing challenges in training, inference, and hardware synthesis.

We report the demonstration of an integrated silicon-rich silicon nitride wavelength converter based on Bragg scattering intermodal four-wave mixing process. The system integrates mode conversion, multiplexing and de-multiplexing functionalities on chip. Broadband signal conversion with a 3dB bandwidth exceeding 70 nm is demonstrated.

We demonstrate 158.4 Tb/s GMI throughput over 120km field-deployed SMF multiplexing 6THz-bandwidth S, C and L lumped amplifiers and optimizing channel power pre-emphasis and constellation entropy to maximize fiber capacity.

We performed simulations and experiments to evaluate the performances of three representative erbium-doped fibre designs for subsea SDM-based systems. Small-core high-NA fibre design which can maintain high power conversion efficiency and deep saturation at low-power operation is favourable for large-scale power-constrained SDM systems.

We introduce a simplified method for calculating the loss function for use in geometric shaping, allowing for the optimisation of high dimensional constellations. We design constellations up to 12D with 4096 points, with gains up to 0.31 dB compared to the state-of-the-art.

A signal-to-signal SNR difference compensation scheme is demonstrated at 4-parallel paths with free-space optical transceivers composed of VCM-based moving lens for the first time. Even with power reduction of 21dB on a link, Q-factor improvement of 4.6 dB and connectivity were confirmed.

We propose and demonstrate a single-ended multimode fiber (MMF)-based shape sensor for robotic arm pose estimation. Swept-wavelength interferometry interrogates weak pointer reflectors micro-machined along the MMF and spatially resolves modal dispersion. Deep learning offers 100% accuracy for classifying six different poses.

Optical network node designs must change to address burgeoning traffic loads. We propose a novel, high-throughput, low-loss, reconfigurable, hierarchical architecture capable of switching whole fibres, flexible-defined bands, down to individual wavelengths, achieving ~10 Pb/s throughput, which will be required by decade end.

This paper uses simulation and experiments to study the scalability of optical wireless receivers based on micro-lens and high-speed photo-diode arrays, verifying a receiver with 3 millimeters aperture operating at a 10 Gbps data rate with a position tolerance of ± 2.7 mm.

We investigate the performance of edge-carrier-assisted phase-retrieval receivers when using multiple dispersive elements. In relevant simulated transmission settings, the carrier-to-signal power ratio can be as low as -4 dB while incurring a 4-dB OSNR penalty compared to theory at the BER of 3.8e-3.

We demonstrate an all-fiber optical amplifier based on parametric-assisted spectral Talbot effect to control the carrier-to-noise ratio (CNR) and the spectral spacing of optical frequency combs. The CNR is enhanced by up to 11 dB while the spacing is multiplied from 11 to 165 GHz.

This experiment is the first to demonstrate the application of secure visible light band free-space optical communication to a hardware-effective no-excessive power penalty phase-encryption scheme. This scheme is applied to a flexible time-domain hybrid PAM signal with a fixed data symbol-to-encryption key bit ratio.

We present a comprehensive study of a field-deployed SDM system based on a coupled-core four-core fiber, providing the first detailed comparison between SDM theory and experimental data. The study includes validation of the model's accuracy and examination of the intensity impulse response (IIR) duration.

We demonstrate, for the first time, a high-capacity NFT-based transmission system, based on PHYDYAS wave-carriers, which is a variant of the FBMC technique, to obtain a significantly improved achievable information rate of 7.2 bits/s for NFDM systems.

We demonstrate phospho-alumino-silicate erbium-doped fibres for an extended L-band amplification to 1628nm, achieving 13.3dB gain and 8.6dB NF at 1628nm, and >20dB gain with <6.9dB NF from 1580-1625nm. At 1625nm, the gain coefficient and the saturated output power were 0.024dB/mW and 17dBm, respectively.

We have proposed a full-duplex, high-capacity optical wireless communication system for an optical wireless data center network. Real-time full-duplex transmission with 112Gb/s pulse amplitude modulation-4 signals have been experimentally demonstrated below the forward error correction threshold with a power penalty of less than 1.5dB.

We present a multifunctional fibre device based on side-polished core-selective multicore fibre couplers and demonstrate spatial path routing by using the couplers as a variable optical power splitter and reconfigurable spatial channel add/drop multiplexer.

We demonstrate 41.3-Tbps net unrepeated transmission in C-band with 37 channels, each carrying >1-Tbps net over 291-km of low-loss high effective-area optical fiber, applying co-Raman amplification, third-order counter-Raman amplification and using 135-GBaud PCS-64QAM signals.

The reliability of In_0.2Ga_0.8As/GaAs nano-ridge photodetectors monolithically integrated on 300 mm Si substrates is first reported. Dark current increases and saturates at 2×10^-5A/cm²at 85 °C after stress, which is still sufficiently low. Carrier emission from pre-existing defects is identified as the dominant degradation mechanism.

A monolithic dual-wavelength laser array based on four phase-shifted grating and equivalent chirp technology is proposed and experimentally demonstrated. The experimental results indicate that the array is capable of generating 66.8-73.6 GHz RF signals, with the signal linewidth less than 176 kHz.

We revisit the achievable information rate (AIR) due to the coupling between digital pre-emphasis and the bandwidth-limited channel under Tx constraints. We propose and experimentally verify, for the first time, a parameter-insensitive, RMS-optimized pre-emphasis filter for shaping high-frequency signal components to enhance the operational AIR.

We demonstrate real-time long-haul transmission with 400G digital subcarrier-multiplexed QSFP-DD coherent pluggable in a live production network, achieving a record post-FEC-error-free reach of 1800-km with 400G-16QAM, 80% longer than all previously publicly announced records.

We investigate a polarization-encoded BB84-QKD transmitter that is simplified from an architectural and technological point-of-view, demonstrating a silicon emitter sourcing a low-complexity polarization modulator for secure-key generation at a raw-key rate of 2.8kb/s and QBER of 10.47%, underpinning the feasibility of an all-silicon QKD transmitter.

We present a compact dual-stage lumped Raman amplifier based on 2x1 km lengths of highly nonlinear fibre (HNLF). The amplifier provides 28.5-dB net gain with 4.5-dB optical noise figure (NF) over a bandwidth of 102 nm from 1525 to 1627 nm.

We compare the capacity of S+C+L systems to C+L and C systems, highlighting the importance of power control techniques for ultra-wideband systems. We also review the benefits of pre-emphasis when maximizing the transmission distance under the constraint of fixed bitrate per channel.