Influence of nonuniform carrier distribution on the polarization dependence of modal gain in multiquantum-well lasers and semiconductor optical amplifiers

We investigate the modal gain seen by transverse-electric (TE) and transverse-magnetic (TM) modes of bulk and multiquantum-well (MQW) lasers given a nonuniform distribution of active region carriers. We find that the dependence of modal gain on the nonuniformity of carrier profile differs for TE and TM modes. This experimentally observable phenomenon is proposed as a measure of carrier density nonuniformity. We discuss the importance of the confinement picture for TE and TM modes, in the generalized presence of some asymmetry, in assuring injection-level independent polarization insensitivity in semiconductor lasers and optical amplifiers.