Energy band calculations for dynamic gain models in semiconductor quantum well lasers

We present a computationally efficient approach to calculating the reduced density of states and dynamic gain in quantum well laser diodes. The valence subband dispersion is calculated along the high-symmetry <100> and <110> axes using the k.p method. The valence subband isoenergy contours are represented by a first order Fourier expansion, which is used to calculate the reduced density of states, so that each photon is allowed to interact with electrons and holes over a finite range of energies. The influence of carrier dynamics upon the gain relies upon the usual relaxation approximation for carrier-carrier interactions. A different approach is adopted for carrier-phonon, interactions due to the carrier kinetic energy threshold for phonon emission, which is needed to realistically represent spectral hole burning and carrier heating effects.