Abstract

A theory of a semiconductor laser is developed that includes the many-body effects due to Coulomb interactions. The theory is valid for both 3-D bulk semiconductors as well as quasi-2-D quantum well structures. We emphasize plasma density-dependent band gap renormalization, broadening due to intraband scattering, and electron–hole Coulomb enhancement. The very short intraband scattering relaxation time allows us to eliminate the interband polarization adiabatically and to introduce a hydrodynamic description of the intraband kinetics. From this general formulation a diffusion equation for the carrier density is derived. The resulting diffusion coefficient decreases with carrier density and laser intensity due to the reduction of the electron drift. We use our theory in the problem of laser gain, index, and side mode instabilities. We show that near the laser operating point, our many-body theory can be approximated by a simple rate equation formalism. However, in contrast to the usual rate-equation theory, the semiconductor rate constants are functions of temperature, tuning, and carrier density.

© 1988 Optical Society of America