CURVED GRATING FABRICATION TECHNIQUES FOR SURFACE-EMITTING DISTRIBUTED FEEDBACK LASERS

We report on techniques for the fabrication of curved waveguide diffraction gratings for use in novel semiconductor laser structures. In particular, we consider the development of concentric-circle gratings to be employed in circularly symmetric, surface-emitting semiconductor lasers. The gratings are defined using electron-beam lithography and subsequently etched into the semiconductor surface by chemically assisted ion-beam etching. Issues to be addressed include grating design requirements, pattern representation, and scan method. We provide examples of how these techniques can be implemented and their impact on the resulting laser performance.