Optical gain of CdZnSe/ZnSe quantum well lasers

Polarization-dependent optical gain of recently demonstrated CdZnSe/ZnSe quantum well lasers is calculated for the first time. Our analysis is based on the multiband effective mass theory (k⋅p theory) and the density matrix formalism with intraband relaxation taken into account. It is shown theoretically that the TE mode gain is significantly larger than the TM mode gain for a wide range of carrier density. Comparison of the room-temperature TE mode gain of CdZnSe/ZnSe quantum well with that of GaAs/AlGaAs quantum well gives disappointing results for the II-VI semiconductor lasers. It is expected that the optical gain of the ZnSe-based semiconductor lasers would be substantially smaller than the optical gain of the GaAs-based semiconductor lasers for a same quantum well width and carrier density.