Surface plasma resonance color filter with wider color gamut

Plasmonic color filters based on nanostructure have the advantages of stable color, small size and good color reproduction, which exhibit promises as an alternative for existing colorant-based filters. However, the color gamut produced by the existing filters is relatively narrow and cannot exceed the sRGB color space so that the limited color gamut limits the further application of the plasmonic color filters. In order to overcome this drawback, we propose a color filter scheme based on surface plasmon resonance (SPR), which can obtain a color range that exceeds the sRGB color space. A special nano pattern structure was etched on the surface of silver film. Under natural light incidence, the nanohole acts as a grating coupler to match the momentum between the photon and the plasma. The surface plasmon resonance occurs on the surface of the metal/medium. In this case, the plasma passes through the aperture and decays into radiant photons after passing through the metal film. By changing the structural parameters of the nano pattern, the plasmon resonance wavelength can be adjusted to obtain different transmission spectra. Converting the transmission spectrum into color coordinates and drawing on the CIE1931 chromaticity diagram can obtain a wide range of colors, and the color range and saturation can exceed the effects that other existing color filters can achieve. Because of the symmetry of the designed nanostructure, the plasmonic color filter is not sensitive to polarized light.