Population pulsations and sidemode generation in semiconductors

This paper applies many-body theory for an electron-hole plasma in semiconductors to multimode semiconductor-laser operation and sidemode generation. We derive third-order laser amplitude and frequency-determining equations and the corresponding propagation equations for multiwave mixing. The equations are similar to those found in multimode gas-laser theory. We include the effects of population pulsations in the total carrier density, but, due to the rapid carrier-carrier scattering, we explicitly suppress spectral hole burning. We also include band-gap renormalization and Coulomb enhancement contributions. The theory is evaluated numerically for the example of nondegenerate four-wave mixing in an amplifier configuration. We discuss the dependence of the idemode intensity on the length of the active medium, the intermode beat frequency, and the pump-wave intensity.