Modeling of self-organized coherence-collapsed and enhanced regime semiconductor fibre grating reflector lasers

A numerical transmission line model for semiconductor lasers with long external fibre cavities and fibre grating reflectors is reported. The model is applied to high-power 980 nm lasers and shows good agreement with experiments in the coherence collapse regime (CCR). The numerical approach has been used to model the saturable absorber in the external cavity of the semiconductor laser with the external fibre grating in the "coherence enhanced regime" (CER). Our simulations show for the first time how line-narrowing evolves in CER lasers.