Coherence enhancement between incoherent lasers based on passive phase compensation

Coherent light beams play an important role in the development of opto‐electronic microwave and terahertz technologies, serving as a source for generating RF carrier signals with very high quality. The authors explore in this work an approach to enhance the coherence between two incoherent lasers so as to provide coherent light beams, and proof‐of‐concept demonstrates a terahertz signal generation with low phase noise. Based on the proposed passive phase compensation technique, the phase noise between two independent lasers can be well suppressed and the carrier to noise ratio in the terahertz regime remains high. In the experiment, the beating phase noise between two independent lasers is reduced from −60.68 dBc/Hz@10kHz to −90.05 dBc/Hz@10kHz at about 280 GHz, which is promisingly applicable in the terahertz photonics community.