Yuancheng Cai

This paper proposes a technology based on high-entropy chaos-driven nonlinear reconstruction physical layer security, which is applied in the optical-electronic hybrid terahertz (THz) architecture. This scheme developed a 335 GHz continuous-wave high-power microwave frequency conversion tube for the transmitter and combined it with an encryption module based on high-entropy embedded in the digital domain at the receiver to complete the collaborative design architecture of photons and electrons. This paper achieved a transmission rate of 16 Gb/s using the 335 GHz continuous-wave traveling-wave tube amplifier delivering >50 dB gain. The transmission distance was set to an outdoor wireless link of 2.2 km. The key space reached 10 ²⁷⁴ . We have, for the first time, to our knowledge, advanced the transmission of secure THz communication links above 300 GHz at the kilometer scale.

High-performance terahertz (THz) sources are increasingly important for next-generation communication, sensing and precision metrology systems. However, existing approaches often rely on complex system architectures, making it difficult to simultaneously achieve low noise and compact photonic-THz synthesizer implementations. Here we demonstrate a compact photonic THz source based on a packaged, self-injection-locked Kerr microcomb using a fiber Fabry–Pérot resonator. The device supports stable soliton operation at a repetition rate of ~ 20 GHz while preserving coherence at THz carrier frequencies. Using a soliton-crystal-derived carrier at 319 GHz, we realize 5 m free-space THz wireless communication with 16- and 64-QAM modulation at symbol rates up to 15 GBd, achieving bit-error rates well below the soft-decision forward-error-correction threshold under turnkey operation. Beyond single-carrier transmission, the microcomb also generates multiple mutually coherent THz carriers near 300 GHz with consistent noise performance. These results establish a compact and low-noise platform for coherent THz synthesis that supports both high-speed communication and parallel multi-channel operation, offering a scalable route toward high-capacity THz systems while reducing device bandwidth requirements and overall system complexity.

An experimental demonstration of photonics-aided terahertz wireless transmission with 128-Gbit/s line rate over 26-km distance at 135 GHz is realized. By employing spectrally efficient frequency division multiplexing (SEFDM) technology with non-orthogonal discrete Fourier transform (NODFT) precoding and multidimensional interference cancellation algorithms to overcome bandwidth and nonlinearity limitations in the transmission system, we achieve a record-breaking, to the best of our knowledge, air interface user rate (AIUR)-distance product in the D-band (110–170 GHz).

Secure and high-capacity transmission is of great importance for future photonics-aided millimeter-wave fiber-wireless systems, especially in W-band links where broadband access and multi-user connectivity are required. To enhance transmission security at the physical layer while maintaining system flexibility, this paper proposes a photonics-aided W-band fiber–wireless scheme using digital frequency conversion and multidimensional interleaved encryption. Two chaotic models are employed to encrypt user bit sequences and symbols with 4D and 2D chaotic sequences, respectively, while interleaving further enhances encryption randomness. Digital frequency conversion generates multiple sub-carriers for collaborative transmission of ciphertext and key. A 2 Gbaud 16QAM encrypted signal is successfully demonstrated in a photonics-aided W-band fiber–wireless coherent transmission system over a 2 m wireless link. Quadrature phase shift keying (QPSK) and 16 quadrature amplitude modulation (16QAM) are adopted, with digital frequency points of 2 GHz for the key, 4.5 GHz for User 1, and 7 GHz for User 2. For QPSK, the bit error rate (BER) of encrypted User 1 and User 2 are 3.39 × 10 ⁻⁴ and 1.01 × 10 ⁻³ ; for 16QAM, they are 3.5 × 10 ⁻³ and 1.4 × 10 ⁻² , respectively. The key space reaches 10 ¹¹² , while the BER at the illegal receiver remains around 0.5. These results show that the proposed scheme supports multi-user transmission and ensures information security, indicating strong potential for future 6 G wireless communication systems.

Integrated systems that combine secure communication with radar jamming are crucial for future intelligent transportation and electronic warfare. This paper experimentally demonstrates a photonics-aided terahertz (THz) integrated sensing and communication (ISAC) system, which provides simultaneous secure communication and cooperative radar deception using a dual-encrypted orthogonal frequency-division multiplexing (OFDM) waveform. The system achieves integrated security protection for both communication and sensing links based on a communication-sensing-encryption (C-S-E) joint waveform. Secure communication is achieved via chaotic encryption with a key space as large as 10 ¹¹⁴ , while radar deception is realized by a phase-encryption model that generates false range targets. Over a 3-m wireless link at 313.2 GHz, the proposed system achieves a 105.8-Gbps data rate and supports multi-user detection with 7-mm radial ranging resolution. Therefore, the proposed scheme effectively degrades adversarial radar detection while enhancing communication security, making it particularly suitable for short-range, high-precision secure ISAC systems.

Faced with the increasingly scarce spectrum resources in low-frequency bands, integrated sensing and communications (ISAC) technology is expanding into millimeter-wave (MMW) and terahertz (THz) frequencies to harness broader bandwidth. To achieve genuine high-performance integration of sensing and communication in these bands, we propose a photonics-aided THz ISAC system based on a step-frequency linear frequency-modulated orthogonal frequency-division multiplexing (SF-LFM-OFDM) waveform. The core idea of this waveform design is to map the sub-LFM pulses onto preallocated OFDM symbols, then perform the inverse fast Fourier transform (IFFT) and add the cyclic prefix (CP) to generate the ISAC signal. This novel scheme incurs minimal additional temporal or spectral cost over the OFDM signal, while fully retaining the inherent large time-bandwidth product (TBP) of the SF-LFM signal to enhance sensing robustness. Leveraging the high time-frequency efficiency of the designed waveform, our experiment demonstrates simultaneous 103.2-Gb/s data transmission and multiuser detection with 7-mm ranging resolution over a 3-m link at 313.2 GHz. Furthermore, this study investigates the impact of the sub-LFM pulse numbers and the power allocation on both the communication and sensing performance.

Terahertz (THz) bands are critical for next-generation wireless fronthaul/backhaul applications. However, they face a fundamental coverage range limitation due to low emission power, severe path loss, and poor receiving sensitivity, especially in photonics-assisted THz systems beyond 300 GHz. To address this limitation, we develop a 335 GHz continuous-wave traveling wave tube amplifier with an output power close to 4 W and a gain of over 50 dB, and construct a novel yet simple diversity receiving scheme to improve the receiving signal-to-noise ratio by ~3 dB. Through hybrid photonic–electronic synergy, combining photonics-assisted THz generation, high-power THz amplification, and spatial diversity reception, a record-breaking kilometer-scale THz wireless communication at 335 GHz—a highly challenging atmospheric window—is demonstrated. We first achieve a net rate of 27.84 Gbit s ⁻¹ over a 2.2 km wireless link—yielding an unprecedented rate–distance product of 61,248 Gbit s ⁻¹ ∙ m—beyond 300 GHz to the best of our knowledge.

In inter-datacenter (DC) elastic optical networks (EONs), dynamic service function chain (SFC) requests arrive and expire on-the-fly, posing significant challenges for efficient resource allocation. Existing heuristic and deep reinforcement learning (DRL)-based methods provide certain optimizations but rely on a full-connection-oriented provisioning scheme, which reserves the entire resource chain for the lifecycle of each SFC request, resulting in suboptimal resource utilization. To overcome these limitations, we propose a dynamic provisioning with store-and-forward scheme to address the dynamic SFC mapping and time scheduling problems based on DRL in inter-DC EONs. In this scheme, the virtual network functions (VNFs) and the light-path provisioning acquire resources only within their respective service times, which are realized by accurate time scheduling. To facilitate the decision-making process of the DRL agent, we decompose the intricate SFC request into several SFC sub-requests, solving them one by one in turn. Evaluations with two topologies demonstrate that our proposed DRL-based method can achieve blocking probability reductions of more than 10.1% and 13.8% when compared with the baselines.

Tidal mobile traffic patterns offer opportunities for efficient Cloud Radio Access Network (CRAN) scheduling by leveraging its disaggregated and virtualized baseband processing, where baseband functions form a virtualized network function service chain (VNF-SC, or RAN slice) deployed across metro access, aggregation, and core networks. By dynamically reconfiguring and migrating RAN slices, processing pools can be powered down during low-demand periods to save energy. However, RAN slice migration causes service disruptions and degrades Quality of Service (QoS), making the tradeoff between energy efficiency and QoS a key challenge in CRAN scheduling. Existing approaches, such as heuristic and Deep Reinforcement Learning (DRL)-based methods, have achieved certain optimizations but rely on fixed scheduling intervals, which require provisioning for peak demand within the interval, leading to resource overprovisioning and inefficiency. To enable flexible and adaptive scheduling, we propose threshold-triggered heuristic-assisted DRL (TT-HA-DRL), which employs a threshold-triggered mechanism based on varying service demands and a heuristic-assisted DRL framework for adaptive RAN slice migration. Heuristic algorithms are used for action pruning to optimize the action space, enhancing scheduling performance. Baseline heuristics are incorporated to construct the Normalized Performance Loss as the reward function, enabling a tradeoff among the multiple optimization objectives. Extensive simulations validate the effectiveness and scalability of the proposed TT-HA-DRL. Compared to fixed-interval HA-DRL, our approach achieves reductions of up to 10.8% in power consumption, 12.3% in migration time, and 23.9% in Maximum Frequency Slot Index (MFSI) in a 30-node network. These results confirm TT-HA-DRL’s ability for elastic and QoS-guaranteed RAN slice scheduling.

To meet the growing demands of next-generation data centers for ultra-high capacity, low latency, and flexible deployment, optical-wireless integrated systems combine the high bandwidth of fiber with the agility of wireless links, enabling scalable and high-speed interconnect solutions. Polarization division multiplexing (PDM) single-input single-output (SISO) links have a simplified architecture design and can double the system capacity through the polarization dimension, but they also introduce more crosstalk and impairments to signal recovery. In this paper, an adaptive Bayes-Adam (ABA) multiple-input multiple-output (MIMO) Volterra nonlinear equalizer (VNE) with high precision and fast convergence is proposed, which better compensates for crosstalk and impairments in dual-polarization (DP) SISO terahertz (THz) transmission systems, including I/Q imbalance, polarization crosstalk, and nonlinear distortion. We experimentally demonstrate a DP-SISO fiber-THz integrated system, which adopts an easily integrable zero-intermediate frequency (Zero-IF) receiver front-end scheme to reduce bandwidth requirements and efficiently receive high baud rate signals. By employing the novel equalization algorithm, we successfully achieve up to 520 Gbit/s single-lane single-carrier wireless air interface rate (WAIR/ch/λ) at 220 GHz with a 20% soft-decision forward error correction (SD-FEC) threshold. This work provides an effective signal processing solution for enabling high-speed, scalable fiber-THz interconnects in future data center networks.