Stability and instability of quantum cascade lasers subject to optical feedback

Abstract

This work shows that optical feedback can either stabilize or destabilize quantum cascade lasers, depending on the alignment of the reflection mirror. On one hand, the laser is insensitive to the common well-aligned optical feedback, and the relative intensity noise has little change against optical feedback. Meanwhile, strong optical feedback well stabilizes the laser frequency and significantly narrows the spectral linewidth, instead of evoking chaotic oscillations. On the other hand, misaligned optical feedback with a tilt angle of the reflection mirror triggers multiple nonlinear dynamics including periodic oscillations, quasi-periodic oscillations, and low-frequency oscillations.