Frequency combs in III-V/SiN integrated hybrid lasers with narrowband mirror

We address the dynamics of a III-V/SiN external cavity hybrid laser with a frequency-selective mirror. Simulations through a set of time-delayed algebraic equations accounting for the narrowband SiN mirror reflectivity demonstrate that CW instability occurs when relaxation oscillations become resonant with the beating between longitudinal modes. In the CW unstable regime, we observe the emergence of frequency combs due to four wave mixing, characterized by a modulation of amplitude and frequency. We then characterize the resulting combs in terms of achievable bandwidth. These results are also confirmed through a more accurate time-domain traveling wave model.