Gd. Sanders et al., CARRIER-CARRIER SCATTERING IN THE GAIN DYNAMICS OF INXGA1-XAS ALYGA1-YAS DIODE-LASERS/, Physical review. B, Condensed matter, 54(11), 1996, pp. 8005-8020
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.