Guided-mode Resonance Filter with Ultra-narrow Bandwidth over the Visible Frequencies for Label-free Optical Biosensor

Abstract

A practical guided-mode resonance filter operating in the visible band of the electromagnetic spectrum is numerically designed in this paper. The filter provides high background transmission (>90%) with almost perfect reflection at resonance wavelengths of 623 nm and 641 nm for TE and TM modes, respectively. Our filter is also characterized by its sensitivity to incident angles, polarizations, and a refractive index of the surrounding environment which are utilized in practical applications such as tunable optical filters, imaging or detection. We show that the resonant transmission spectral response can be used for highly sensitive, a potential label-free refractive index biosensor having sensitivities of 90 nm/RIU and 103 nm/RIU, and figure of merits of 1.93 and 2.13 for TM and TE polarizations, respectively.