Effects of strain and Coulomb interaction on gain and refractive index in quantum-well lasers

The eigenstates of the coupled-band Luttinger Hamiltonian are used to derive modified optical Bloch equations for strained layer semiconductor heterostructures. An average effective-mass approximation is introduced, and the single-plasmon-pole approximation for the screened Coulomb interaction is extended for the multiple-subband case. Spectra of the optical absorption/gain and of the antiguiding (linewidth enhancement) factor are computed by use of a high-density Padé approximation for the quantum-well susceptibility. We compare results for various strained and unstrained systems.