Polarization dependent study of gain anisotropy in semipolar InGaN lasers

The optical gain of single quantum well laser structures on semipolar (1122)-GaN in dependence of the optical polarization and the resonator orientation has been studied by variable stripe length method. The c'-[1123] resonator shows maximum gain in TE mode, followed by the m-[1100]-resonator with extraordinary polarization. The anisotropic gain behaviour is explained by valence sub-band ordering and birefringence of the wurtzite crystal, resulting in a modification of the transition matrix element for stimulated emission. Measurements are accompanied by 6 x 6 k . p band structure calculations and gain analysis.