Anomaly in the excitation dependence of the optical gain of semiconductor quantum dots

Optical gain behavior of semiconductor quantum dots is studied within a quantum-kinetic theory, with carrier-carrier and carrier-phonon scattering treated using renormalized quasiparticle states. For inhomogeneously broadened samples, we found the excitation dependence of gain to be basically similar to quantum-well and bulk systems. However, for a high quality sample, our theory predicts the possibility of a decreasing peak gain with increasing carrier density. This anomaly can be attributed to the delicate balance between state filling and dephasing. © 2006 The American Physical Society.