Infrared spectral filters based on guided-mode resonance with subwavelength structures

摘要

We study experimentally and theoretically band-pass filters based on guided-mode resonances in free-standing metal-dielectric structures with subwavelength gratings. A variety of niters are obtained: polarizing filters with 1D gratings, and unpolarized or selective polarization filters with 2D gratings, which are shown to behave as crossed-1D structures. In either case, a high transmission (up to ≈ 79 %) is demonstrated, which represents an eight-fold enhancement compared to the geometrical transmission of the grating. We also show that the angular sensitivity strongly depends on the rotation axis of the sample. This behavior is explained with a detailed description of the guided-mode transmission mechanism.