466.4-Gbit/s PCS-64QAM wireless transmission enhanced by dual-polarized SISO link and vector-quantized variational autoencoders.

We successfully demonstrate photonics-assisted single-carrier 466.4 Gbit/s wireless transmission over 20 km SSMF and 6 m single-input single-output (SISO) wireless delivery at 92.5 GHz.

Photonics-aided exceeding 200-Gb/s wireless data transmission over outdoor long-range 2 × 2 MIMO THz links at 300 GHz.

Outdoor long-range terahertz (THz) communications often come at the expense of transmission rate. Moreover, the practicability of the single polarization optical/THz link, which is commonly used in the previous long-range THz demonstrations based on photonics, is extremely limited by the following two fatal defects. One is relying on active polarization control, and the other is not supporting the transparent bridging of optical polarization division multiplexed (PDM) signals for mature coherent optical communication networks.

Adaptive feedback-driven probabilistic shaping for high-order modulation formats in a fiber-THz seamless integration system at 320 GHz.

In this Letter, we propose a novel, to the best of our knowledge, adaptive feedback-driven probabilistic constellation-shaping (FBD-PCS) method based on the robustness evaluation criteria and employ variational autoencoder (VAE)-based equalizers to implement polarization demultiplexing and nonlinear equalization for the recovery of high-order PCS-QAM signals. We experimentally demonstrate the fiber-THz 2 times 2 MIMO system with a net rate of 366.4 Gbit/s using dual-polarization 40 Gbaud PCS-64QAM signal over a 20 km SSMF and 6 m wireless link.

Spectrally efficient multi-service fiber-wireless access in low-cost direct-detection THz system at 300 GHz.

This Letter demonstrates a novel, to the best of knowledge, overlapping single-sideband (OSSB) transmission scheme for spectrally efficient multi-service fiber-wireless (FiWi) access in a low-cost direct-detection (DD) THz system. Utilizing the proposed OSSB scheme, user data from different services can share the same spectrum resource yet can be successfully demodulated via one cost-effective DD THz receiver in conjunction with the Kramers-Kronig (KK) based SSB field reconstruction and look-up table (LUT) enabled signal separation algorithms. A proof-of-principle experiment is conducted.

Nonlinearity mitigation in a fiber-wireless integrated system based on low-complexity autoencoder and BiLSTM-ANN equalizer.

We propose and experimentally demonstrate an intelligent nonlinear compensation method using a stacked autoencoder (SAE) model in conjunction with principal component analysis (PCA) technology and a bidirectional long-short-term memory coupled with ANN (BiLSTM-ANN) nonlinear equalizer for an end-to-end (E2E) fiber-wireless integrated system. The SAE-optimized nonlinear constellation is utilized to mitigate nonlinearity during the optical and electrical conversion process. Our proposed BiLSTM-ANN equalizer is primarily based on time memory and information extraction characteristics, which can compensate for the remaining nonlinear redundancy.

Photonics-aided integrated sensing and communications in mmW bands based on a DC-offset QPSK-encoded LFMCW.

The evolution of mobile communications towards millimeter-wave (mmW) bands provides a strong opportunity for the seamless integration of radar and wireless communications. We present a photonics-aided mmW integrated sensing and communications (ISAC) system constructed by photonic up-conversion using a coherent optical frequency comb, which facilitates zero frequency offset of the resulting mmW signal. The sensing and communications functions are enabled by a joint waveform that encodes a DC-offset QPSK signal on a linear frequency-modulated continuous wave (LFMCW) in baseband.

Demonstration of 144-Gbps Photonics-Assisted THz Wireless Transmission at 500 GHz Enabled by Joint DBN Equalizer.

The THz wireless transmission system based on photonics has been a promising candidate for further 6G communication, which can provide hundreds of Gbps or even Tbps data capacity. In this paper, 144-Gbps dual polarization quadrature-phase-shift-keying (DP-QPSK) signal generation and transmission over a 20-km SSMF and 3-m wireless 2 × 2 multiple-input multiple-output (MIMO) link at 500 GHz have been demonstrated. To further compensate for the linear and nonlinear distortions during the fiber-wireless transmission, a novel joint Deep Belief Network (J-DBN) equalizer is proposed.

Real-time demonstration of 103.125-Gbps fiber-THz-fiber 2 × 2 MIMO transparent transmission at 360-430 GHz based on photonics.

In this Letter, we experimentally demonstrate the first real-time transparent fiber-THz-fiber 2 × 2 multiple-input multiple-output (MIMO) transmission system with a record line rate of 125.516 Gbps at 360-430 GHz based on photonic remote heterodyning, hybrid optoelectronic down-conversion, and commercial digital coherent modules. The 103.

Chromatic dispersion immune microwave photonic phase shifter based on double-sideband modulation.

A chromatic dispersion (CD) immune microwave photonic phase shifter (MPPS) based on double-sideband (DSB) modulation is proposed and demonstrated. An optical spectrum processor introduces the phase shift to the MPPS. The DSB signals along two orthogonal polarizations are demodulated to two RF signals with both quadrature amplitude and phase items, transferring the CD-induced power fading to the phase item of the synthetic RF signals.

Photonic generation of background-free binary and quaternary phase-coded microwave pulses based on vector sum.

A photonic microwave phase-coded pulse generator is proposed and experimentally demonstrated based on the principle of vector sum. The key component of the proposed pulse generator is an integrated polarization-division multiplexing Mach-Zehnder modulator (PDM-MZM) and a 90° hybrid coupler. By properly setting the data sequences applied to the specially biased PDM-MZM, binary and quaternary phase-coded microwave pulses (PCMPs) that are free from the background signals can be generated.

All-optical generation of binary phase-coded microwave pulses without baseband components based on a dual-parallel Mach-Zehnder modulator.

In this paper, we propose an all-optical system for the generation of binary phase-coded microwave pulses without baseband components. The scheme is based on a dual-parallel Mach-Zehnder modulator (DPMZM). By properly applying the coding signals and the microwave signals to the precisely biased DPMZM, accurate π phase shift binary phase-coded microwave pulses without baseband components can be generated.

Equivalent photonic switch for microwave frequency shift keying signal generation.

A photonic microwave frequency shift keying (FSK) signal generator is proposed and experimentally demonstrated based on an equivalent photonic switch (EPS). The EPS is constructed using a polarization-multiplexing dual-drive Mach-Zehnder modulator (PM-DMZM). By properly controlling the data sequences and RF signals applied to the PM-DMZM, microwave FSK signals with flexible frequency intervals can be obtained.

Optical network solution to the synchronization of distributed coherent aperture radar.

Distributed coherent aperture radar (DCAR) is an important direction for next-generation radar due to its high sensitivity. The challenge to realize DCAR is the synchronization among geographically distributed radar units. We propose an optical network for DCAR synchronization.

Broadband chromatic-dispersion-induced power-fading compensation for radio-over-fiber links based on Hilbert transform.

A Hilbert-transform-based broadband chromatic dispersion (CD) compensation scheme for radio-over-fiber links is proposed and experimentally demonstrated. By constructing a Hilbert transform path, CD-induced phase shifts, which initially lead to periodic power fading of the output RF signals, are transferred to the phases of the RF signals. As a result, the powers of the output RF signals are free from the effect of CD in a broadband frequency range.

2D optically controlled radio frequency orbital angular momentum beam steering system based on a dual-parallel Mach-Zehnder modulator.

An optically controlled system for generating and continuously steering radio frequency (RF) signals with double orbital angular momentum (OAM) modes is proposed and experimentally demonstrated. The optical carrier's utilization efficiency can be doubled through the distinct electro-optical modulation, which is based on two single-sideband modulation operations on a single optical carrier through a customized dual-parallel Mach-Zehnder modulator. A constructive antenna phase feeding method of a circular antenna array for collectively forming and steering an OAM radio beam is proposed and illustrated.

Anti-dispersion phase-tunable microwave mixer based on a dual-drive dual-parallel Mach-Zehnder modulator.

An optically-controlled phase-tunable microwave mixer based on a dual-drive dual-parallel Mach-Zehnder modulator (DDDP-MZM) is proposed, which supports wideband phase shift and immunity to power fading caused by chromatic dispersion. By using carrier-suppressed single side-band (CS-SSB) modulation for the local oscillator (LO) signal and carrier-suppressed double side-band (CS-DSB) modulation for the input signal, no vector superposition for the same output microwave frequency occurs, making the system immune from power fading caused by chromatic dispersion. Phase tuning is achieved by shifting the phase of the LO signal, and direct electrical tuning of the wideband microwave input signal is avoided, thus supporting large working bandwidth.