Influence of Asymmetric Gain Suppression on Relative Intensity Noise Properties of Multimode Semiconductor Lasers

We introduce modeling and simulation of the noise properties associated with types of modal oscillations induced by scaling the asymmetric gain suppression (AGS) in multimode semiconductor lasers. The study is based on numerical integration of a system of rate equations of 21-oscillating modes taking account of the self- and cross-modal gain suppression mechanisms. AGS is varied in terms of a pre-defined parameter, which is controlled by the linewidth enhancement factor and differential gain. Basing on intensive simulation of the mode dynamics, we present a mapping (AGS versus current) diagram of the possible types of modal oscillations. When the laser oscillation is hopping multimode oscillation (HMMO), the spectra of relative intensity noise (RIN) of the total output and hopping modes are characterized by a sharp peak around the relaxation oscillation (RO) frequency and a broad peak around the hopping frequency. The levels of RIN in the regimes of single-mode oscillation (SMO) are much lower than those under HMMO, and the mode-partition noise is two order of magnitudes lower.