CARRIER-CARRIER SCATTERING IN THE GAIN DYNAMICS OF INXGA1-XAS ALYGA1-YAS DIODE-LASERS/

Ultrafast optical nonlinearities in semiconductors play a central role in determining transient amplification and pulse-dependent gain satur ation in diode lasers. Both carrier-phonon and carrier-carrier scatter ing are expected to determine the gain dynamics in these systems. We p resent a relaxation-time approximation model for carrier-carrier scatt ering in strained-layer lasers. The carrier-carrier scattering rates a re determined using the quasiequilibrium distribution functions for a given background carrier density. The distribution function to which t he photoexcited distribution relaxes is a Fermi-Dirac function where t he chemical potential and temperature are self-consistently chosen so that both particle number and energy are conserved in the carrier-carr ier scattering process. The relaxation approximation makes the problem an effective one-dimensional problem which can then be solved directl y for the carrier distributions using an adaptive Runge-Kutta routine. This procedure is less computationally intensive than a full Monte Ca rlo simulation. The results show that the inclusion of carrier-carrier scattering improves previous results where only carrier-phonon scatte ring was included and that carrier-carrier scattering is necessary to produce heating of the carriers in the high-energy tails.