Side-mode gain in grating-tuned extended-cavity semiconductorlasers: investigation of stable single-mode operation conditions

摘要

In semiconductor lasers, nonlinear phenomena inside the activenmedium change the side-mode gain with respect to the staticnthreshold-gain. For a given side mode, the sign and the magnitude of thenchange depend on the lasing-mode optical power and on the wavelengthndetuning from the lasing mode. If the side-mode gain is enhanced,nmode-hopping can occur toward a side mode whose loss is higher than thenlasing-mode one. Conversely, in the case of side-mode-gain suppression,nthe side-mode loss can be smaller with no mode-hop. In this paper,neffects of carrier-density pulsation, carrier heating, and spectral-holenburning on the conditions of stable single-mode operation inngrating-tuned single-mode extended-cavity semiconductor lasers areninvestigated. Taking into account the external cavity spectralnselectivity and mode coupling, we present a theoretical analysis ofnexperimental results. We perform calculations that compare well with thenexperimental data obtained with a 1.55-Μm extended-cavity laser