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-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, we have successfully generated a sub-THz signal at 108.7 GHz, characterized by a 3-dB linewidth of less than 2 kHz and a side-peak suppression ratio of 46 dB. Moreover, by merely adjusting the power and frequency of the optical injection, it is possible to generate sub-THz signals with comparably high spectral purity across a range from 100 GHz to 300 GHz.