Cost-Effective Photonic Terahertz Signal Generation Using a Single Wavelength Tunable Laser for Communication and Radar Applications

Abstract

Photonics-based terahertz (THz) technology has emerged as a key enabler for future 6G networks, offering ultrawide bandwidth and cross-domain applications such as high-capacity communications and high-resolution radar. However, conventional THz photomixing architectures rely on optical frequency combs or dual lasers, which impose severe limitations in terms of size, weight, power, and cost (SWAP-C). In this article, we propose a cost-effective photonic THz signal generation scheme based on only a single electro-optically wavelength tunable laser (WTL). Moreover, two representative applications are investigated. For THz wireless communications, the proposed system employs a fiber-delayed self-multiplexer to realize on-off keying modulation via wavelength switching, together with a T-flip-flop-based decoding method that enhances data rate scalability and transmission security. An error-free 100 Mbit/s transmission at 280 GHz validates the feasibility of this low-SWAP-C communication system. For radar applications, the same single-WTL platform enables linearly frequency-modulated (LFM) THz signal generation with waveform reconfigurability. Both sawtooth and triangle LFM THz signals are achieved, providing enhanced bandwidths of 11.5 GHz and 5 GHz with chirp rates exceeding 0.027 GHz/ns at the 300-GHz-band. These results highlight the versatility of single-WTL-based photomixing, presenting a low-SWAP-C solution for future photonic THz communication and radar systems.