Near-UV narrow bandwidth optical gain in lattice-matched III–nitride waveguides

We demonstrate optically-pumped waveguides grown on freestanding GaN substrate featuring AIInN claddings and GaN/Al0.1Ga0.9N multiple quantum wells exhibiting narrow bandwidth (3.8 nm) optical gain around 370 nm. Due to the high refractive index contrast between the cladding layers and the active region, the confinement factor is as high as 48% and net modal gain values in excess of 80 cm(-1) are measured. The results agree well with self-consistent calculations accounting for built-in electric field effects and high carrier density related phenomena. These results open interesting perspectives for the realization of more efficient near-UV lasers and optical amplifiers. (C) 2018 The Japan Society of Applied Physics