Dynamic analysis of directly modulated Fabry–Perot laser diodes using time-domain modeling with random noise fluctuations

Abstract

Based on time-domain laser modeling, we have systematically evaluated multi-mode excitation and mode competition in directly modulated Fabry–Perot laser diodes biased with different current levels. In our simulation, random noise fluctuations depending on the bias current are included since they play an important role in determining the number of lasing modes. Multi-mode excitation and mode competition occurred at the biased current below the threshold current can be explained with the aid of frequency chirp at turn-on and gain difference in between '0' and '1' bits. The positive frequency chirp (25 GHz for lasers biased below the threshold current and 15 GHz for lasers biased above the threshold current) affects to enhance the probability of multi-mode excitation in low-frequency region during turn-on delay.