Variable optical reflectance of a self-supported Si grating

Abstract

Variable reflectance of a self-supported Si grating mirror is reported. A grating suspended in air consisted of an array of 300nm wide, 300nm thick, and 20μm long beams. The period of the grating was varied with an electrostatic microactuator from 600to720nm. A broadband reflection in the wavelength longer than the grating period was observed, which was caused by a resonant interference of the light wave propagating along the grating similar to the guided-mode resonant gratings. Increasing the period of the grating with a microactuator, the reflection spectrum changed. The results were explained by the theoretical calculations based on rigorous coupled-wave analysis.