EFFECT OF THE MODAL INTERACTION ON THE SPECTRAL LINEWIDTH IN THE NEARLY SINGLE-MODE SEMICONDUCTOR-LASERS

A statistical numerical simulation method is proposed by which the accumulation of phase fluctuations and the spectral linewidth in semiconductor lasers are investigated theoretically. In the case of single mode, the result is quite in agreement with that by small signal approximation instead of being 4 times larger. In the case of nearly single mode, the linewidth of the main mode is increased somewhat but not too seriously by the side mode. The overestimation and its cause of the results obtained by a Monte Carlo method used by other authors recently is noted, and a power-independent linewidth component of the side mode of the order of 100 MHz agreeing with experiment is obtained where the small signal approximation is not applicable.