Wideband reflectors fashioned with freestanding HFO2 resonant gratings

Abstract

This paper proposes the design and fabrication of guided-mode resonant broadband reflectors operating in the visible band under TE polarization. The structure is composed of a freestanding subwavelength periodic HFO 2 grating with an air cavity between the grating and the silicon substrate. The proposed wideband reflectors fashioned with freestanding HFO 2 resonant gratings are implemented on an HFO 2 /AlN/Silicon platform by combining ion beam etching (IBE) of HFO 2 film and wet etching of AlN. The optical responses of the designed freestanding HFO 2 gratings are analyzed by the rigorous coupled-wave analysis(RCWA) method. More than 98% reflectance over an 50∼52nm spectral range spanning 396∼470nm was shown in the simulation of two reflectors with different parameters.