Evidence for state filling effect on high speed modulation dynamics of quantum well lasers

By using different separate confinement structures for otherwise identical quantum well lasers, we find experimentally that the differential gain can vary over a factor of three, which significantly affects the high speed modulation bandwidth in such lasers. These observations are in agreement with the predictions of a theory of modulation dynamics which accounts for the carrier population in the optical confining region of the separate confinement structure (state filling effect) in quantum well lasers.