A theoretical study of transmission color filters with double metal layers for the visible spectrum is presented. The device
consists of five parts: the transparent substrate, the dielectric grating, the first metal layer, the second metal layer and the
cover dielectric layer. The first metal layer is disposed in the trench of the dielectric grating. The second metal layer,
having the same thickness as the first metal layer, overlies on the top surface of the dielectric grating. And the cover
dielectric layer is formed on the metal layers. By using rigorous couple-wave analysis (RCWA), the transmission
characteristics are analyzed as a function of the duty cycle, the thickness of the dielectric grating, the thickness of the
metal layers and the period. Based on the simulation results, a high-performance color filter is designed by optimizing
the structural parameters. The grating periods are 280, 220, and 170nm for the red, green, and blue filters, respectively.
For the red color filter the center wavelength was 650nm and its corresponding transmission 84%, for the green color one
the center wavelength was 550 nm and its corresponding transmission 83%, while for the blue color one the center
wavelength was 440nm and its corresponding transmission 83%. The bandwidths of the filters are about 100nm.
Accordingly, the color filters not only perform better in filtering light but also produce high color purity. Additionally,
each color light has high transmission. They are suitable for filtering in liquid crystal devices.