Intensity‐tunable guided mode resonance reflectance filter with dual channels

Abstract

An intensity-tunable reflectance filter with an unetched grating that is based on guided mode resonance is proposed. The unetched grating is designed for simplifying the fabrication proceeds and avoiding the errors of etching. The dual resonant wavelength channels are calculated by rigorous coupled-wave analysis to be at 747.3 and 786.5 nm. Theoretical and experimental data indicate that the intensity of the spectral reflectance at the peak wavelength of 747.3 nm increases monotonically with variation of the azimuthal angle from 0° to 90°. Conversely, the intensity of the spectral reflectance decreases monotonically under the same conditions at the resonant wavelength of 786.5 nm. It is found experimentally that the intensity can be tuned via the azimuthal angles, and this agrees well with the results of the theoretical analysis. In addition, the influence of the structural parameters on the value of the wavelength separation between the dual resonance channels is analysed, and the electric field distributions at the resonant wavelengths are presented.