Color Filters for 0.255um Pixels

OSA Optics Express paper "Absorptive metasurface color filters based on hyperbolic metamaterials for a CMOS image sensor" by Jongwoo Hong, Hyunwoo Son, Changhyun Kim, Sang-Eun Mun, Jangwoon Sung, and Byoungho Lee from Seoul National University shows a possibility of a straight Bayer pattern with 0.255um pixels. By straight Bayer, I mean no 2x2, 3x3 or similar color grouping.

"Metasurface color filters (MCFs) have attracted considerable attention thanks to their compactness and functionality as a candidate of an optical element in a miniaturized image sensor. However, conventional dielectric and plasmonic MCFs that have focused on color purity and efficiency cannot avoid reflection in principle, which degrades image quality by optical flare. Here, we introduce absorptive-type MCFs through truncated-cone hyperbolic metamaterial absorbers. By applying a particle swarm optimization method to design multiple parameters simultaneously, the proposed MCF is theoretically and numerically demonstrated in perceptive color on CIELAB and CIEDE2000 with suppressed-reflection. Then, a color filter array is numerically proven in 255 nm of sub-pixel pitch."

The work is supported by the Samsung University R&D program.