Collision broadening of optical gain in semiconductor lasers

Abstract

The energy-dependent intraband relaxation with polar-optical-phonon scattering is incorporated in the calculation of the linear gain and the refractive index change of the GaAs injection laser with an undoped active region. Comparison with the conventional model, which assumes a constant intraband relaxation, shows that it is difficult to fit the overall gain spectra exactly by single, energy-independent intraband-relaxation time. Moreover, the calculated gain spectra wth phonon broadening show strong temperature dependence due to the change of the relaxation time and the Fermi functions.