Optical gain in group-III nitride lasers

First-principles band calculations were performed to provide a set of material parameters that can be used to model optical gain in AlN, GaN, InN and their alloys, both in strained and unstrained configurations. A key result from this calculations is that the cubic approximation is not appropriate for the group-III nitrides. The results from the band structure calculations are incorporated to a microscopic laser theory based on the semiconductor Bloch equations, which give a consistent treatment of the carrier-carrier Coulomb interactions.