Mirror-Assisted Self-Injection Locking of a Laser to a Whispering-Gallery-Mode Microresonator

Self-injection locking is a dynamic phenomenon, which provides passive stabilization of a laser emission frequency via resonant optical feedback. The stabilization coefficient depends on the level of the feedback and quality factor of the external resonant structure creating the feedback. A conventional self-injection locked laser (SIL) based on a dielectric cavity involves barely tunable resonant Rayleigh scattering (RRS). In this work we study theoretically a scheme of a SIL via a high-$Q$ microresonator with a drop-port coupled mirror, in which the optical feedback level is optimally adjusted by tuning the drop-port mirror coupling. We show that the additional reflector can improve the laser stabilization and power handling efficiency if compared with the classic RRS-based scheme.