Microfabrication Of Photonic Crystal Mirrors For Optoelectronic Devices.

Abstract

Photonic bandgap crystals are expected to be useful in defining microcavities for modifying spontaneous emission and as high reflectivity mirrors. Here, we use these photonic crystals as end-mirrors of edge-emitting GRINSCH lasers. These single quantum well lasers were grown by molecular beam epitaxy (MBE) and consist of waveguide structures which are in excess of 1.5 micrometers in thickness. To define a high-reflectivity photonic crystal mirror on the edge of these laser stripes, we use a surface mask of PMMA on top of an epitaxially deposited AIAs masking layer. After electron beam exposure of the resist and definition of the 100nm diameter holes through the GaAs cap layer and the 200 nm thick AIAs mask layer, high temperature field oxidation of the AIAs is performed at 340°C for 1.5 hours. This oxidizes the AIAs and forms a very robust etch mask. The hexagonal arrays of 100nm holes are then transferred to a depth of 2 microns through the laser waveguide structure so as to overlap with the optical field in the laser (Figure 1). The output mirror for the laser stripe consists of a standard cleaved facet.