Dependence of optical gain on direction of optically pumped cavity on (0001)-plane for InGaN/GaN multiple quantum well structure

In this work, we demonstrate the theoretical prediction about the dependence of the optical gain on the orientation of the laser cavity in (0001) plane for the strained InGaN/GaN multiple quantum well structure. The net modal gain of the InGaN/GaN multiple quantum well has been measured by variable excitation stripe length method for optically pumped cavity along each crystal orientation on (0001) plane. The measured optical gain for the cavity along the [1̄21̄0] direction is larger than any other oriented cavities. 'Crystal orientation' is confirmed to be a parameter related to the optical gain for GaN-based strained structure. The results reveal that the best cavity orientation of GaN-based edge-emitting laser is in [1̄21̄0] direction.