Optically pumped GaInN/GaN-DFB lasers: overgrown lasers and vertical modes

The laser operation of GaInN/GaN distributed feedback lasers (DFB) with sep arate confinement double hetero or multi quantum well structures on SiC is demonstrated. The separate confinement heterostructures were realized by ov ergrowing the dry etched DFB gratings. Optically excited lasing is observed with emission wavelengths between 402 and 421 nm, depending linearly on th e grating period. The laser thresholds are compared to laser thresholds of non overgrown DFB lasers. Furthermore, the wavelengths selectivity of DFB l asers is used to study vertical modes in laser structures grown on sapphire . In a thick asymmetric laser structure, higher vertical modes can be disti nguished because of their different effective refractive index eta(eff). In thin heterostructures. the vertical ground mode is lasing. (C) 1999 Elsevi er Science S.A. All rights reserved.