Highly Efficient Color Filter Incorporating a Thin Metal–Dielectric Resonant Structure

A highly efficient color filter that takes advantage of an ultrathin metal (Al)-dielectric (TiO 2 ) resonant structure, where a subwavelength metallic grating is deposited as cladding in a planar dielectric waveguide, is demonstrated. A selective spectral response was obtained by virtue of the guided mode resonance between the diffracted mode and waveguide mode. The center wavelengths for the blue, green, and red filters were found to be 430, 520, and 630 nm, and the corresponding 3 dB bandwidths were 67, 84, and 80 nm, respectively. All three filters provided an overall transmission exceeding 70% and a satisfactory color image.