Experimental analysis of room-temperature optical gain in GaInN-GaN and GaN-AlGaN double heterostructures and quantum wells

We have studied the optical gain in nitride-based laser structures. We find evidence for excitonic gain at room temperature. A strong polarization dependence of the gain is observed, in accordance with the band structure. We have used optical gain spectroscopy employing the stripe excitation method in order to elucidate the mechanisms of optical gain in GaInN-GaN and GaN-AlGaN double heterostructures and quantum wells.