Stabilization of a whispering gallery mode self-injection locked laser based on phase difference control

We investigate the application of feedback control of phase difference between the whispering gallery mode microresonator and the laser cavity, for the stabilization of self-injection locking. By analyzing the relationship between phase difference and microresonator transmitted light intensity, as well as the characteristics of selected phase shift devices and controller, the phase difference is successfully maintained at the set point. Through this phase difference control mechanism, the semiconductor laser with a high-quality microresonator coupled and connected by optical fibers exhibits a stable self-injection locking. Key performance metrics include a narrow linewidth of around 200 Hz and a minimum normalized output wavelength Allan deviation of 1×10⁻¹⁰. This approach presents a promising and reliable solution for the self-injection locked laser stabilization.