Visible light communication (VLC), combining wireless communication with white lighting, has many advantages. It is free of electromagnetic interference, is rich in spectrum resources, and has a gigabit-per-second (Gbps) data rate. Laser diodes (LDs) are emerging as promising light sources for high-speed VLC communication due to their high modulation bandwidth. In this paper, we demonstrate a red/green/blue (R/G/B) LDs based VLC system with a recorded data rate of 46.41 Gbps, employing discrete multitone (DMT) and adaptive bit-loading technology to achieve high spectral efficiency (SE). The emission characteristics and transmission performance of R/G/B-LDs are discussed. The optimal data rates of R/G/B-LDs channels are 17.168/14.652/14.590 Gbps, respectively. The bit-error-ratio (BER) of each channel satisfies the 7% forward-error-correction (FEC) threshold (3.8×10⁻³) and greatly approaches the channel Shannon limit.

High-speed visible light communication (VLC) using light-emitting diodes (LEDs) is a potential complementary technology for beyond-5G wireless communication networks. The speed of VLC systems significantly depends on the quality of LEDs, and thus various novel LEDs with enhanced VLC performance increasingly emerge. Among them, InGaN/GaN-based LEDs on a Si-substrate are a promising LED transmitter that has enabled VLC data rates beyond 10 Gbps. The optimization on the period number of superlattice interlayer (SL), which is a stress-relief epitaxial layer in a Si-substrate LED, has been demonstrated to be an effective method to improve Si-substrate LED’s luminescence properties. However, this method to improve LED’s VLC properties is barely investigated. Hence, we for the first time experimentally studied the impact of SL period number on VLC performance. Accordingly, we designed and fabricated an integrated 4 × 4 multichromatic Si-substrate wavelength-division-multiplexing LED array chip with optimal SL period number. This chip allows up to 24.25 Gbps/1.2 m VLC transmission using eight wavelengths, which is the highest VLC data rate for an InGaN/GaN LED-based VLC system to the best of our knowledge. Additionally, a record-breaking data rate of 2.02 Gbps over a 20-m VLC link is achieved using a blue Si-substrate LED with the optimal SL period number. These results validate the effectiveness of Si-substrate LEDs for both high-speed and long-distance VLC and pave the way for Si-substrate LED design specially for high-speed VLC applications.

In the upcoming 6G, the integrated sensing and communication (ISAC) system in the millimeter wave (MMW) band will have a vital role in numerous application scenarios, enhancing the convenience of our lives. The photonic-based MMW ISAC system can exploit the broad bandwidth of photonic devices, significantly improving system performance. Furthermore, the use of photonic devices enables the seamless integration of the ISAC system with the fiber-wireless network. In this paper, we proposed a simple-structured photonic-based W-band ISAC system, incorporating optical fiber transmission into the system. Additionally, we designed integrated waveforms for time-frequency-division multiplexing (TFDM), allowing for flexible tradeoffs between data rate, range resolution, and detection distance according to the requirements of application scenarios. As a proof-of-concept, a photonic-based ISAC system for the fiber-wireless network with flexible TFDM waveforms at 96.5 GHz over 10-km fiber transmission was demonstrated, achieving adaptive access rates from 15 to 60 Gbit/s after transmission over 1-m free space, and adaptive range resolutions from 1.53 to 4.39 cm. Moreover, this paper provides a detailed analysis of the causes of system distance error and corresponding solutions. In the experiment, the distance error of the proposed system can be reduced to less than 3 cm after external calibration.

Aside from ambient light noise, shot noise, and linear/nonlinear effects, strong low-frequency noise (LFN) severely affects the signal quality in LED-based visible light communication (VLC) systems, which hinders the implementation of data-driven end-to-end (E2E) deep learning approaches in real LED-VLC systems. We present a deep learning-based autoencoder to deal with this challenge. A novel modeling strategy is proposed to bypass the influence of the LFN and other low signal-to-noise ratio data when training the channel model of our E2E framework. The deep learning-based autoencoder then embeds the differentiable channel model and learns to combat the majority of channel impairments. In the E2E LED-VLC experiment, 1.875 Gbps transmission is achieved under the 7% HD-FEC threshold, 0.325 Gbps faster than the baseline. The E2E framework is robust to signal bias and amplitude variations, implying dimming support in the indoor environment.

Coherent passive optical network (PON) has been proposed to support the next generation high-speed optical access network owing to the superior receiver sensitivity and thereby the extended power budget for 100 G-and-beyond. In addition, PON's flexibility and adaptability are gaining increasing interest. Flexible PON is believed to be a powerful solution in optimizing the overall capacity based on the available channel conditions, i.e., the optical path loss (OPL) and the associated signal-to-noise ratio and nonlinearity impairments of the different groups of optical network units. In this study, we demonstrate the rate-flexible coherent TDM-PON in burst-mode based on probabilistic-shaping (PS) QAM modulations and local oscillator (LO) power adjustment technology, achieving a 300G peak rate and ultra-wide dynamic range. The principle, the burst-mode frame generation as well as the burst-mode signal processing are discussed in detail. To indicate the overall performance of achievable capacity and flexibility, a new metric, namely, dynamic-range and net-rate product ( DRNRP ) is introduced as the indicator to show the optimized throughput. Finally, we experimentally demonstrated a flexible coherent TDM-PON in burst-mode based on 25-GBaud PS-QAMs with the dynamic range of >35-dB in back-to-back. A record DRNRP up to 7,104 dB·Gbps was achieved in the current system with net data rate varying from 255-Gbits/s to 85-Gbits/s as the OPL varies over 20-km fiber transmission.

The integration of sensing and communication (ISAC) in millimeter-waves (MMW) will play an important role in future 6G applications. Photonics-based radar sensing and communication systems have the advantages of high bandwidth in terms of high-resolution sensing and high-speed data transmission and can be inherently integrated with fiber-optic networks. To support flexible application scenarios, in this paper, we proposed and experimentally demonstrated an MMW photonics-based flexible ISAC system with adaptive signal waveforms for a W-band fiber-wireless integrated network. Photonics-based W-band ISAC signals are generated by heterodyning two free-running external cavity lasers. Microwave photonics-based radar signal processing supports centralized and seamless fiber-wireless communication and sensing networks. In our proposed system, orthogonal frequency-division multiplexing (OFDM) and linear frequency modulation (LFM) signals were combined by frequency-division multiplexing to share this bandwidth. Therefore, we can adaptively allocate bandwidths to OFDM and LFM signals according to the application requirements and realize a flexible ISAC system with high-speed communication and high-resolution radar sensing. As a proof-of-concept, a flexible W-band fiber-wireless ISAC system at 96.5 GHz over 10-km fiber transmission was demonstrated, achieving adaptive access rates from 5.98 to 41.48 Gbit/s after transmission over 1-m free space, and adaptive sensing resolutions from 1.53 to 6.94 cm with the distance error after calibration less than 4 cm. The performance of both communication and sensing under different bandwidth ratios was also studied.