Highly transmissive subtractive color filters based on an all-dielectric metasurface incorporating TiO₂ nanopillars

Transmissive subtractive color filters are proposed and demonstrated that take advantage of an all-dielectric metasurface based on a lattice of TiO₂ nanopillars (NPs), rendering a high transmission efficiency that exceeds 90%. TiO₂ NP elements have been created that exhibit a high aspect ratio. Specifically, a series of lithographic processes are conducted to form a narrow and deep hole in the photoresist, which is accompanied by atomic layer deposition of TiO₂. A broad palette of vivid colors encompassing the visible band has been obtained by adjusting the NP diameter for a constant duty ratio of 0.35. For the NP resonator, the electric and magnetic field profiles in conjunction with the scattering cross-sections have been meticulously investigated to theoretically validate that the resonant transmission dips are primarily governed by the simultaneous excitation of an electric dipole and a magnetic dipole via Mie scattering.