Properties of GaN-based laser diodes with a buried-ridge structure

The buried-ridge structure was introduced to GaN-based laser diodes for the purpose of realizing an index-guided structure in order to control the dif ference of effective refractive indexes between the inside and outside of t he lasing area and to stabilize the lasing mode. Low-temperature-grown AlxG a(1 - x)N was used as the burying layer, and it was found that the refracti ve-index difference can be controlled by adjusting the Al content in the Al xGa(1 - x)N burying layer independent of the ridge dimensions. As a result of fabricating LDs with different Al contents, we found that Al content sho uld be more than 30% in order to form an index-guided structure. The optimu m refractive-index difference was estimated by fitting with the calculation . The LD with a buried-ridge structure, in which Al in the burying layer wa s more than 30%, had desirable properties as an index-guided waveguide. (C) 2000 Elsevier Science B.V. All rights reserved.