Comparison of optical losses in dielectric-apertured vertical-cavity lasers

The performance of vertical-cavity lasers (VCL's) employing dielectric apertures formed by lateral oxidation or wetetch undercutting of an AlAs layer on a common substrate are compared, Although both device types performed well, extracted optical losses from the wet-etch undercut structures exceed those of AlAs-oxide apertured lasers, The difference in performance is attributed to optical scattering losses specific to the aperture fabrication method, enhanced by loss from the larger index of refraction discontinuity of the air-gap aperture relative to the AlAs-oxide aperture.