Ultrathin high-efficiency, variable-color filters with an adjustable bandwidth by combining a cavity resonator and a dielectric film

In this paper, we design and numerically investigate ultrathin high-efficiency, variable-color filters. The color filters, based on a cavity resonator covered with a compensated dielectric film, promise an adjustable spectral bandwidth while preserving the same resonant wavelength. A broad color gamut and widely tuned color saturation can be obtained by gradually varying the cavity depth and the top mirror thickness, respectively. The numerical results show that the transmitted peak wavelength remains unchanged with the angle of incident range from 0 to 60°for TM polarization and the transmission efficiency is above 65% at the resonant peak wavelength. Moreover, the physical mechanism of the device is investigated. The light field is mainly concentrated in the cavity, leading to the strong resonant effect. The proposed designs can be fabricated more easily by the deposition methods for the practical applications.