Development of a Loop Animated Full-Color Metasurface Hologram with High Color Reproduction

This study reports a looped full-color holographic movie using dielectric metasurface that exhibits high color reproducibility. Calculations were made to separate the colors in the target image into those represented by the three de-sign wavelengths (443 nm, 532 nm and 633 nm). Then, by reproducing and superimposing their intensity distributions, we succeeded in demonstrating high color reproducibility. Silicon nitride (SiN) was selected as a metasurface mate-rial for its low absorption with a reasonably high refractive index at the visible region. Compared to conventional color holograms made of single-crystal silicon (c-Si), SiN has excellent transparency, although its refractive index is lower than that of c-Si. Therefore, fabrication with a very high aspect ratio is required. This study solves the difficulty and reports the successful color meta-surface hologram cinematic animation. In order to align the viewing angle of the RGB image, the projected images for each component were superimposed by keeping the ratio between the projected wavelength and pixel periods constant. Furthermore, Three-color metasurface holograms were arranged in a square ring to loop the cinematic animation. The average transmittance in each frame image was 84.9%, which was higher than in previous studies. Finally, a loop-moving full-color holographic image consisting of 30 frames was successfully reproduced at a maxi-mum speed of 5 frames per second.