MODE PARTITION IN SEMICONDUCTOR-LASERS WITH OPTICAL FEEDBACK

Random noise processes induce mode partition fluctuations in semicondu ctor lasers. Mode partition depends on laser parameters and modulation current. However, external optical feedback can also increase mode pa rtition noise. In this paper a numerical solution of multimode noise-d riven rate equations with time-delayed terms is utilized to investigat e mode partition in semiconductor lasers with reflecting feedback. We consider photon statistics of the main and side modes in semiconductor lasers under both CW operation and dynamic operation. Probability-den sity curves for the main and side modes are shown. The feedback-induce d change of photon statistics of the main and side modes is clearly se en. Numerical results indicate that, if the laser used is exposed to r eflections, the mode discrimination requirement to suppress the buildu p of laser-cavity longitudinal side modes can be increased. If mode di scrimination is insufficient for avoiding the excitation of side modes , the feedback-induced power penalty will depend on the fiber dispersi on.