Polarization-dependent GaN surface grating reflector for short wavelength applications

This study proposes a one-dimensional sub-wavelength grating structure on GaN surface which behaves as a reflector for transverse-electric polarized light in the blue wavelength range. The rigorous coupled-wave analysis method was used to analyze the effects of various structural parameters on the reflectance spectra of the grating. Based on the optimal design, a GaN surface grating reflector (SGR) was fabricated using holographic lithography and dry etching processes. It showed reflectance that exceeded 90% over a 60-nm bandwidth. The obtained experimental results were in good agreement with simulated ones. The SGR has an advantage of structural simplicity, which should greatly facilitate the fabrication and integration of high reflectors on GaN-based short-wavelength photonic devices.