Abstract

We calculate sidemode gain and coupling spectra in semiconductor gain media for mode spacings both small compared to the carrier–carrier relaxation rates, as well as comparable to these rates as predicted by Binder et al.¹ The sidemode gain and coupling coefficients reduce to those of Ref. 2 for small beat frequencies and to those for the inhomogeneously broadened two-level system for beat frequencies comparable to the carrier–carrier scattering rates. We find population pulsations sharpen the spectral holes burned by the strong mode and double their depth. This suppresses nearby modes and encourages modes further away. For the large carrier–carrier relaxation rates of Ref. 1, the predicted sidemode gain is smaller than the main mode gain, leading to single-mode operation. For smaller relaxation rates, sidemode gain can easily exceed the single-mode gain. In addition, we find that gain and coupling spectra are sensitive to the k dependence of the carrier-carrier relaxation rates and provide a way to measure them.

© 1991 Optical Society of America