GaAs-based subwavelength grating on an AlOx layer for a vertical-cavity surface-emitting laser

A GaAs-based subwavelength grating on a thick (similar to 3/4*lambda at 1300 nm) AlOx layer is designed, fabricated, and characterized. The AlOx layer as a low-index medium is oxidized from a 640-nm Al0.9Ga0.1 As layer. The layer contraction of the Al0.9Ga0.1 As layer after wet oxidation to AlOx is 4.9%. We fabricated GaAs-based subwavelength gratings on the AlOx layer showing a high reflectivity of 90% in the 1300-nm wavelength range, consistent with the simulation results. Such GaAs-based subwavelength gratings can be used as high-contrast grating mirrors for narrow-linewidth VCSELs, improving the mechanical stability and simplifying the device fabrication. (C) 2020 Optical Society of America under the terms of the OSA Open Access Publishing Agreement