Influence of thermal effects in microresonators on the locking range in self-injection locking of laser diodes

Abstract

Stable narrow-linewidth lasers generated by self-injection locking systems have revolutionized applications from optical frequency metrology to astronomy. However, the dynamics for the self-injection locking system are intrinsically intertwined with thermal effects, which can generate a nonnegligible resonance drift in the microresonator and result in large detuning from the required regime. In this paper, we introduce the thermal effect, depending on the photon number, into self-injection locking systems with Rayleigh backscattering. We obtain a set of time-domain rate equations to describe the dynamics of laser-diode–cavity–microresonator systems and derive analytical formulas for effective detuning. The analytical results match well with our numerical simulations, and the effective detuning locking position moves forward as the value of the thermal effect coefficient decreases. We also analyze the dependence of the locking range and stable range on thermal effects, and our calculations show that, based on our approach, the stable range can be optimized effectively and the locking range is extended. Our results have the potential to optimize laser diode frequency stabilization experiments.