Miniaturized low-phase-noise microwave sources play a pivotal role in cutting-edge technologies, including 6G mobile communications, autonomous driving radar systems, non-destructive testing, real-time imaging, and biosensing applications. The significance of low phase noise lies in its ability to minimize bit error rates, optimize quadrature modulation efficiency, and enhance the accuracy of radar and imaging systems. In recent years, the optically generated microwave approach, which leverages frequency locking of dual laser diodes, has attracted considerable interest. This method effectively reduces phase noise through common-mode rejection mechanisms.

However, conventional electrical feedback frequency-locking techniques necessitate intricate active servo control systems, resulting in a substantial increase in device volume—approximately 0.1 cubic meters. In stark contrast, self-injection locking (SIL) based on optical feedback circumvents the need for electrical feedback loops. This innovation not only streamlines the system's architecture and control mechanisms but also significantly reduces its overall footprint. Furthermore, SIL boasts a broader noise suppression bandwidth and demonstrates superior performance compared to electrical feedback, particularly in mitigating high-frequency-offset noise.