Heating of electrons in an injection semiconductor laser

The dependence of the temperature of a system of nonequilibrium electrons on the injection current is derived for cw and pulsed injection semiconductor lasers using a published model of quantum transitions in such lasers. It is shown that pumping of a laser with current pulses of sufficiently short duration (tens of nanoseconds) results in a significant difference between the electron and crystal lattice temperatures, which increases on increase in the pulse amplitude. This increase shifts the emission line, governed by the spectral position of the optical gain maximum, toward shorter wavelengths, in contrast to the usual shift toward longer wavelengths observed in the case of pumping with a constant current or with pulses of sufficiently large duration (in excess of 100 ns). These theoretical results are supported by data obtained in an experiment on a gallium arsenide homojunction laser.