Design of hybrid metal-dielectric (Al-TiO2) metasurfaces RGB color filters

Abstract Color filter arrays play a vital role in spectrally discriminating light into red, green and blue (RGB) bands—widely utilised in color cameras and display technology. Existing absorptive dye color filters exhibit low transmission efficiencies and require thicknesses several times that of the lateral pixel sizes they cover in order to achieve sufficient spectral discrimination (leading to cross-talk). Structural color generation based on metasurfaces may alleviate the challenges of dye-based counterparts, due to potential of achieving high pixel resolution within sub-wavelength thicknesses and easily customizable filter functions. However, achieving high efficiency transmission modes for RGB colors (with high saturation) remains challenging. In this work, we present designs for CMOS-material-compatible high efficiency RGB color filters based on hybrid metal-dielectric metasurfaces composed of aluminium (Al) and titanium dioxide (TiO2) nanoblocks. The interaction between plasmonic and Mie resonances results in hybrid modes with transmission efficiencies of 80% and a full-width-half-maximum ranging between 42 and 67 nm. By optimizing geometric parameters, we achieve highly saturated transmission-mode colors, covering a wide color gamut of the standard RGB (sRGB) color space. The presented filter designs offer a route toward high efficiency color filters for application across multiple technologies including optical imaging, spectral sensing, and mead-mounted displays.