GaN-based high-power laser diodes

We report our recent progress on GaN-based laser diodes (LDs) which will be applied as a light source in high-density optical storage systems. Recentl y we achieved a lifetime of more than 500 hours under continuous-wave opera tion with a constant power 20 mW at 25 degreesC using GaN-based LDs with a standard ridge structure. We also report the potential of GaN-based LDs wit h another structure of a buried-ridge. The far-field pattern of the LDs wit h a buried-ridge structure strongly depended on the Al content of the AlxGa 1-xN burying layer. This dependency showed that the device characteristics change from gain-guiding to refractive index-guiding. The critical point wa s around x = 0.30 of an Al content which corresponds to Deltan = 0.007 of a lateral index step. It was, therefore, found that the optical transverse m ode can be controlled by adjusting the Al content of the AlxGa1-xN burying layer. (C) 2001 Elsevier Science B.V. All rights reserved.