Lasing and optical gain around 500 nm from optically pumped lasers grown on c-plane GaN substrates

Using the variable stripe length method we demonstrated positive net optical gain around 500 nm for an optically pumped laser with InGaN/GaN multiple quantum wells grown on c-plane freestanding GaN substrates. We found that owing to low optical gain, reducing optical losses is crucial to increasing lasing wavelength. We demonstrated lasing at 502 nm by using a 3-mm-long cavity with cleaved facets.