Fano-like resonances in nanostructured thin films for spatial filtering

Fano-like resonant coupling of electromagnetic radiation with planar waveguiding modes of nanostructured thin films is proposed and realized experimentally. Different from conventional Fano coupling to compact resonators with the discrete spectrum, we report Fano-like coupling to infinitely extended planar waveguiding modes of the spatially unbound system. We fabricated the films by the ion beam sputtering method on nano-modulated substrates. The observed Fano-like process shows extremely strong sensitivity with respect to the wavelength and especially to the incidence angle of the radiation and can potentially be used for frequency and spatial filtering of light in transmission/reflection through/from such nanostructured thin films.