Experimental demonstration of 8190-km long-haul semiconductor-laser chaos synchronization induced by digital optical communication signal.

Common-signal-induced synchronization of semiconductor lasers have promising applications in physical-layer secure transmission with high speed and compatibility with the current fiber communication. Here, we propose an ultra-long-distance laser synchronization scheme by utilizing random digital optical communication signal as the common drive signal. By utilizing the long-haul optical coherent communication techniques, high-fidelity fiber transmission of the digital drive can be achieved and thus ultra-long-distance synchronization is expected.

Large range wavelength demodulation for ultra-short fiber Bragg gratings based on an arrayed waveguide grating and a convex optimization algorithm.

A wavelength demodulation method for ultra-short fiber Bragg grating (US-FBG) sensors based on an arrayed waveguide grating (AWG) and a convex optimization algorithm is proposed and demonstrated. Instead of measuring the output power ratio of the two adjacent AWG channels as previously done, in this work the wavelength demodulation is realized by reconstructing the US-FBG spectrum. The principle of spectral reconstruction involves using an AWG to sample the spectral information of US-FBG and constructing underdetermined matrix equations with the obtained prior information on transmission responses and the detected output power from multiple AWG channels.

Photonics-assisted self-interference cancellation for in-band full-duplex integrated sensing and communication transceiver.

In-band full-duplex (IBFD) operation is essential for both sensing-centric and communication-centric integrated sensing and communications (ISAC) systems. Both types require the monostatic transceiver to overcome the technical challenge of self-interference (SI). To address this challenge, a photonics-assisted self-interference cancellation (SIC) scheme for an IBFD ISAC transceiver is proposed and experimentally demonstrated.

Design of an on-chip integrated multi-channel comb filter based on the Bragg grating structure.

We designed a multi-channel comb filter generation scheme with nearly consistent channel numbers and free spectral range (FSR) in standard 220-nm-thick silicon-on-insulator (SOI) technology. This scheme relies on the formation of optical microcavities using Bragg grating structures, which serve as reflectors. By precisely designing the optical path length of the microcavity, we can generate optical filters with a specific number of channels.

Multi-channel broadband optical chaos generation assisted by phase modulation and CFBG feedback.

In this paper, we propose a novel and simple multi-channel broadband optical chaos generation scheme based on phase modulation and chirped fiber Bragg grating (CFBG). Firstly, phase modulation is introduced to generate more new frequency components to broaden the spectrum of the phase chaos. Meanwhile, the accumulated dispersion from CFBG distorts the intensity chaos, converts phase chaos to intensity chaos, and weakens the laser relaxation oscillation.

Total net-rate of 27.88 Tb/s full C-band transmission over 4,550 km using 150 km span length and high-gain EDFA amplification.

We experimentally demonstrate a total net-rate of 27.88 Tb/s for C-band wavelength-division multiplexing (WDM) transmission over an ultralong span-length of 150 km. It is the largest net capacity × span-length product of 4182 Tb/s·km for C-band, single-core, standard single-mode optical fiber transmission over a length of more than 3,000 km.

Millimeter-wave over fiber integrated sensing and communication system using self-coherent OFDM.

Orthogonal frequency-division multiplexing (OFDM) waveform is highly preferred as a dual-function candidate for integrated sensing and communication (ISAC) systems. However, the sensitivity to both carrier frequency offset (CFO) and phase noise greatly impedes its applications in millimeter-wave ISAC systems. Here, we propose and experimentally demonstrate a photonic millimeter-wave ISAC system employing the virtual-carrier-aided self-coherent OFDM technique, wherein a digitally-generated local oscillator is transmitted along with the OFDM signal.

Compact optical 90° hybrid based on a wedge-shaped 2 × 4 MMI coupler and a 2 × 2 MMI coupler on a thin-film lithium niobate platform.

We performed an experimental demonstration of a wedge-shaped optical 90° hybrid coupler on the thin-film lithium niobate (TFLN) platform, utilizing a paired-interference-based 2 × 4 multimode interference (MMI) coupler and a general-interference-based 2 × 2 MMI coupler. The fabricated optical 90° hybrid coupler has a compact footprint with a width of 18 µm and a length of 134 µm. In a coherent receiving system, the hybrid coupler directly connects to the balanced photodiode array, eliminating the need for waveguide crossings or cascaded phase shifters.

Fast fiber nonlinearity compensation method for PDM coherent optical transmission systems based on the Fourier neural operator.

Fiber nonlinearity compensation (NLC) is likely to become an indispensable component of coherent optical transmission systems for extending the transmission reach and increasing capacity per fiber. In this work, we introduce what we believe to be a novel fast black-box neural network model based on the Fourier neural operator (FNO) to compensate for the chromatic dispersion (CD) and nonlinearity simultaneously. The feasibility of the proposed approach is demonstrated in uniformly distributed as well as probabilistically-shaped 32GBaud 16/32/64-ary quadrature amplitude modulation (16/32/64QAM) polarization-division-multiplexed (PDM) coherent optical communication systems.

Regulation of cluster synchronization in multilayer networks of delay coupled semiconductor lasers with the use of disjoint layer symmetry.

In real-world complex systems, heterogeneous components often interact in complex connection patterns and could be schematized by a formalism of multilayer network. In this work, the synchronization characteristics of multilayer network composed of semiconductor lasers (SLs) are investigated systematically. It is demonstrated that the interplay between different layers plays an important role on the synchronization patterns.

SASFF: A Video Synthesis Algorithm for Unstructured Array Cameras Based on Symmetric Auto-Encoding and Scale Feature Fusion.

For the synthesis of ultra-large scene and ultra-high resolution videos, in order to obtain high-quality large-scene videos, high-quality video stitching and fusion are achieved through multi-scale unstructured array cameras. This paper proposes a network model image feature point extraction algorithm based on symmetric auto-encoding and scale feature fusion. By using the principle of symmetric auto-encoding, the hierarchical restoration of image feature location information is incorporated into the corresponding scale feature, along with deep separable convolution image feature extraction, which not only improves the performance of feature point detection but also significantly reduces the computational complexity of the network model.

Adaptive polarization control for a fiber system based on the optimized AdamSPGD algorithm.

In this work, an adaptive control scheme based on the optimized AdamSPGD algorithm is proposed to maintain the stable state of polarization (SOP) of the optical signal in a fiber system. The search space can be reduced by half with the guidance of the physical equation of optical intensity that passes through a liner polarizer, leading to an increase in the speed and stability. Moreover, the robustness is guaranteed by the adoption of AdamSPGD as the optimization object.

Predicting nonlinear multi-pulse propagation in optical fibers via a lightweight convolutional neural network.

The nonlinear evolution of ultrashort pulses in optical fiber has broad applications, but the computational burden of convolutional numerical solutions necessitates rapid modeling methods. Here, a lightweight convolutional neural network is designed to characterize nonlinear multi-pulse propagation in highly nonlinear fiber. With the proposed network, we achieve the forward mapping of multi-pulse propagation using the initial multi-pulse temporal profile as well as the inverse mapping of the initial multi-pulse based on the propagated multi-pulse with the coexistence of group velocity dispersion and self-phase modulation.

Wideband chaos synchronization using discrete-mode semiconductor lasers.

Optical chaos communication encounters difficulty in high-speed transmission due to the challenge of realizing wideband chaos synchronization. Here, we experimentally demonstrate a wideband chaos synchronization using discrete-mode semiconductor lasers (DMLs) in a master-slave open-loop configuration. The DML can generate wideband chaos with a 10-dB bandwidth of 30 GHz under simple external mirror feedback.

Long-range high-spatial-resolution distributed Brillouin sensing enabled by correlation-domain encoding.

A hybrid aperiodic-coded Brillouin optical correlation domain analysis (HA-coded BOCDA) fiber sensor is proposed to achieve long-range high-spatial-resolution distributed measurement. It is found that high-speed phase modulation in the BOCDA actually forms a special energy transformation mode. This mode can be exploited to suppress all detrimental effects parasitized in a pulse coding-induced cascaded stimulated Brillouin scattering (SBS) process and thereby enable the HA-coding to reach its full potential to improve the BOCDA performance.

Real-time adaptive optical self-interference cancellation for in-band full-duplex transmission using SARSA(λ) reinforcement learning.

Self-interference (SI) due to signal leakage from a local transmitter is an issue in an in-band full-duplex (IBFD) transmission system, which would cause severe distortions to a receiving signal of interest (SOI). By superimposing a local reference signal with the same amplitude and opposite phase, the SI signal can be fully canceled. However, as the manipulation of the reference signal is usually operated manually, it is difficult to ensure a high speed and high accurate cancellation.

Experimental demonstration of 201.6-Gbit/s coherent probabilistic shaping QAM transmission with quantum noise stream cipher over a 1200-km standard single mode fiber.

A probabilistic shaping (PS) quadrature amplitude modulation (QAM) based on Y-00 quantum noise stream cipher (QNSC) has been proposed. We experimentally demonstrated this scheme with data rate of 201.6Gbit/s over a 1200-km standard single mode fiber (SSMF) under a 20% SD-FEC threshold.

Photonic reservoir computing using a self-injection locked semiconductor laser under narrowband optical feedback.

Photonic time-delay reservoir computing (TDRC) using a self-injection locked semiconductor laser under optical feedback from a narrowband apodized fiber Bragg grating (AFBG) is proposed and numerically demonstrated. The narrowband AFBG suppresses the laser's relaxation oscillation and provides self-injection locking in both the weak and strong feedback regimes. By contrast, conventional optical feedback provides locking only in the weak feedback regime.

Performance improvement of coherent optical chaos communication using probabilistic shaping.

We numerically investigate the effects of probabilistic shaping on the performance improvement of coherent optical chaos communication. Results show that the decryption bit-error ratio (BER) of the 16-ary quadrature amplitude modulation (QAM) signal decreases upon increasing the probabilistic shaping factor. It is predicted that the BER of 10-GBd 16QAM can be decreased by one order of magnitude.

Photonic super-resolution millimeter-wave joint radar-communication system using self-coherent detection.

A millimeter-wave (MMW) joint radar-communication (JRC) system with super-resolution is proposed and experimentally demonstrated, using optical heterodyne upconversion and self-coherent detection downconversion techniques. The point lies in the designed coherent dual-band constant envelope linear frequency modulation-orthogonal frequency division multiplexing (LFM-OFDM) signal with opposite phase modulation indexes for the JRC system. Then the self-coherent detection, as a simple and low-cost means, is accordingly facilitated for both de-chirping of MMW radar and frequency downconversion reception of MMW communication, which circumvents costly high-speed mixers along with MMW local oscillators and, more significantly, achieves the real-time decomposition of radar and communication information.

Digitized radio-over-fiber transmission based on probabilistic quantization codeword shaping.

To improve the receiver sensitivity of the digitized radio-over-fiber (DRoF) transmission system, a vector quantization scheme based on probabilistic quantization codeword shaping (PQCS) is proposed. The PQCS performs quantization bits (QBs) rematching on the original codebook to optimize the proportion distribution of level '0' and level '2' in 4-Pulse Amplitude Modulation (PAM-4) for improving system sensitivity. A 16-Quadrature Amplitude Modulation (16-QAM) DRoF transmission system using intensity-modulation/direct-detection is employed to experimentally verify the proposed scheme.

Modeling of a multi-parameter chaotic optoelectronic oscillator based on the Fourier neural operator.

A model construction scheme of chaotic optoelectronic oscillator (OEO) based on the Fourier neural operator (FNO) is proposed. Different from the conventional methods, we learn the nonlinear dynamics of OEO (actual components) in a data-driven way, expecting to obtain a multi-parameter OEO model for generating chaotic carrier with high-efficiency and low-cost. FNO is a deep learning architecture which utilizes neural network as a parameter structure to learn the trajectory of the family of equations from training data.

Blind and low-complexity modulation format identification based on signal envelope flatness for autonomous digital coherent receivers.

Modulation format identification (MFI) is a critical technology for autonomous digital coherent receivers in next-generation elastic optical networks. A novel and simple MFI scheme, to the best of our knowledge, based on signal envelope flatness is proposed without requiring any training or other prior information. After amplitude normalization and partition, the incoming polarization division multiplexed (PDM) signals can be classified into quadrature phase shift keying (QPSK), 8 quadrature amplitude modulation (QAM), 16QAM, and 64QAM signals according to envelope flatnesses , , and of signals in different amplitude ranges.