Fabrication of ultrathin color filters for three primary colors using guided-mode resonance in silicon subwavelength gratings

We fabricate reflection color filters for three primary colors using silicon two-dimensional triangular-lattice subwavelength gratings on the same quartz substrate. The grating periods are 480, 390, and 300 nm for red, green, and blue filters, respectively. All of the color filters have the same thickness of 100 nm, which enables the simple fabrication of a color filter array. Maximum reflectances of 75 and 46% are obtained at wavelengths of 647.1 and 522.1 nm for the red and green filters, respectively. The blue filter has a double-peaked spectrum with a reflectance of 30% at the peak wavelengths of 450.0 and 502.7 nm. By rigorous coupled-wave analysis, the dimensions of each color filter are designed, and the calculated theoretical reflectance is compared with the measured one.