Guided-mode resonant filters incorporating the Brewster effect

Guided-mode resonance (GMR) effects are observed in dielectric and semiconductor thin-film structures comprising diffractive and waveguide layers1,2. High-efficiency resonances are realizable under zero-order conditions imposed by a diffractive element with suitably high spatial frequency such that all higher-order diffracted waves are evanescent. For parametric conditions such that one of these evanescent waves couples to a (leaky) waveguide mode, a resonance occurs with associated strong power exchange between the propagating zero-order waves. This resonance coupling effect is typically represented as spectral (with constant angle of incidence) or angular (with constant wavelength) variation of the diffraction efficiency of the transmitted and reflected waves. Theoretical and experimental studies1–10 have illustrated the feasibility of utilizing this basic effect for numerous applications11.