Investigation of angle-insensitive grating color filters at periods much smaller than the wavelength of incidence

We designed and simulated one-dimensional (1D) and two-dimensional (2D) reflective grating color filters inside the aluminized polyethylene (PE) film. The filters have several advantages: high angle insensitivity (up to 45° for the 1D filter, 40° for the 2D filter), high reflectance at non-resonant wavelengths, deep resonance dips, and a large color gamut. Both structures are characterized by with their grating periods being much smaller than the wavelength of incidence. A grating modal analysis was utilized to reveal the physical mechanism behind such structures that exhibit angle-insensitive spectral responses which are favored in the fields of color display and packaging.