Abstract
Color filters have been used for a variety of applications such as liquid crystal displays (LCDs). Conventional color filters produce color by absorbing unnecessary wavelengths, which cause energy loss. Additionally, as an important optical element in the LCDs, polarization filters are required since liquid crystals have polarization dependency. We propose hybrid plasmonic-dielectric subwavelength grating (SWG) filters, which have both functions of wavelength- and polarization- selectivities in one filter. The SWG filter consists of a three-layered one-dimensional SWG, in which a plasmonic layer, a buffer layer, and a dielectric layer are stacked on a substrate. Using rigorous coupled-wave analysis, three kinds of the SWG filters with periods of 300, 380, and 500 nm are designed to produce blue, green, and red colors, respectively. For transverse-magnetic polarized light, each SWG filter shows high transmittance in each color region with good wavelength selectivity, which functions as a color filter. Maximum transmittances of 72.4%, 72.6%, and 73.5% are obtained at wavelengths of 445, 540, and 650 nm for the blue, green, and red filters, respectively. For transverse-electric polarized light, each SWG filter shows high reflectance in the whole visible region, which functions as a broadband band-stop filter.
