Analysis of cross-correlation coefficients between mode fluctuations in semiconductor lasers

Using the rate equations with the Langevin operators, we calculate the cross-correlation coefficients of the fluctuations between longitudinal modes of semiconductor lasers. From their signs and magnitudes, we can explain the distribution of the energy between those different modes. Experimental results on nearly single-longitudinal-mode lasers confirm that "nonlasing" modes exchange energy with the "lasing" mode and not with each other. We also show that rate equations give some information on the mode partition coefficient in terms of mean power in the longitudinal modes.