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 HFO2 grating with an air cavity between the grating and the silicon substrate. The proposed wideband reflectors fashioned with freestanding HFO2 resonant gratings are implemented on an HFO2/AlN/Silicon platform by combining ion beam etching (IBE) of HFO2 film and wet etching of AlN.
The optical responses of the designed freestanding HFO2 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.