We present a detailed analysis of a semiconductor hybrid laser exploiting spectral control from an external photonic waveguide circuit that provides frequency-selective feedback. Based on a spatially resolved transmission line model (TLM), we have investigated the output power, emission frequency, and the laser spectral linewidth. We find that, if the feedback becomes weaker, the spectral linewidth is larger than predicted by previous models that are based on a modified mean-field approximation, even if these take a strong spatial variation of the gain into account. The observed excess linewidth is caused by additional index fluctuations that are associated with strong spatial gain variations.
Fan, Y., Lammerink, R. E. M., Mak, J., Oldenbeuving, R. M., van der Slot, P. J. M., & Boller, K. J. (2017). Spectral linewidth analysis of semiconductor hybrid lasers with feedback from an external waveguide resonator circuit. Optics express, 25(26), 32767-32782. https://doi.org/10.1364/OE.25.032767