Partition noise in semiconductor lasers under CW and pulsed operation

A numerical model which simulates the mode partition noise in semiconductor lasers under CW as well as pulsed operation is presented. The noise levels in the individual modes under CW operation are in agreement with those predicted by an analytic small-signal model. Under simulated pulse modulation with pulse repetition frequencies of 633 MHz and 2.2 GHz, the probability density functions for the relative photon numbers in the individual modes are found. The data allow for an evaluation of the mode partition parameter . For the central modes, factors are in the range of 0.31-0.42, depending on bias level and modulation frequency. Weaker side modes carrying less than 5 percent of the total output have factors smaller than 0.16.