Infrared spectral filtering based on guided-mode resonance structure
Abstract
We present the experimental study of a new design of band-pass filter based on guided-mode resonances in a free-standing metal-dielectric structure with subwavelength gratings. Component consists of a subwavelength gold grating with narrow slits deposited on a silicon nitride membrane. High optical transmission is measured with up to 78% transmission at resonance. Experimental angularly resolved spectra are presented: they reveal the role of the diffracted orders and of the waveguide eigenmode in the resonance. Spectra have a typical profile of Fano resonances: we show that this profile is due to interferences between a direct transmission channel through the 0th order, and an indirect transmission channel which results from the excitation by the ±1 diffracted orders of a waveguide eigenmode.