Onset of sidemode buildup in semiconductor lasers

Certain aspects of the multimode problem have been treated by extending the work of M. Sargent et al. (1988) to beat frequencies as big as or bigger than the carrier-carrier scattering rate. For those relatively large frequencies, the individual k-dependent carrier densities undergo pulsations that are too fast to allow the carriers to be described by quasi-Fermi-Dirac distributions. In general the carrier-density evolutions are described by a Boltzmann scattering equation. The carrier-carrier scattering contributions in this equation have been approximated by a simple relaxation term. Using this approach, sidemode gain and coupling coefficients that include hole burning and population pulsation contributions very similar to those for inhomogeneously broadened two-level systems have been found.