Photonic Generation of Tunable Sub-THz Signals Using Two Semiconductor Lasers with Highly Asymmetric Mutual Coupling

This research investigates an approach for generating tunable sub-terahertz (sub-THz) signals using the period-one nonlinear dynamics of optically injected semiconductor lasers. Specifically, a novel all-optical stabilization method based on highly asymmetric mutual injection is proposed, aimed at enhancing the spectral purity of the produced sub-THz signals. As a result, a sub-THz signal at a frequency of 108.7 GHz with a 3-dB linewidth below 2 kHz and a side-peak suppression ratio (SPSR) of 46 dB is generated. Furthermore, sub-THz signal generation with similar high spectral purity, ranging from 100 GHz to 300 GHz, can be achieved by simply adjusting the power and frequency of the optical injection.