Angle Robust Reflective Subtractive Color Filter Using Titanium Dioxide Metasurface and Aluminum Mirrors

Recently, color filters have been used for high quality resolution color imaging and printing in subwavelength scale. In this paper, a reflective subtractive color filter with excellent color contrast has been demonstrated. In the proposed filter, titanium dioxide nanocuboids have been integrated with aluminum mirrors at the top and bottom of them. Due to the creation of magnetic dipole in titanium dioxide nanocuboids, a resonance occurs in the visible spectrum, which the resonance wavelength could be tuned over the whole visible range through the adjustment of the nanocuboid side size. By utilizing aluminum patches on both sides of the nanocuboids, the efficiency of more than 70% and the bandwidth of less than 35 nm have been attained. The proposed filter exhibits high incident angular tolerance such that by increasing the incident light angle from 0 to 60 degree, the resonance wavelength has very poor variation and maintains the same bandwidth and efficiency. Also, the proposed filter is polarization-independent due to its symmetric geometry. These advantages facilitate the function of the suggested filter in imaging and displays with high brightness.