Optical Metasurface-Based Holographic Stereogram

Holographic stereography providing binocular depth cues is one of the most promising technologies for 3D displays. However, conventional holographic stereograms based on micrometer-scale pixels suffer from multiple diffraction orders and narrow viewing angles. Optical metasurfaces with sub-wavelength-scale features have recently been leading amongst the state-of-the-art technologies in 3D holograms but employing only monocular depth cues. Here, a novel method is presented based on optical metasurfaces for obtaining a binocular holographic stereopsis. The demonstrated optical metasurface is an ensemble of several hologram pieces, which produce the different 2D projections of the target 3D structure depending on the observation direction, and displays the holographic stereogram of 25 x 25 x 25 mu m(3) over a wide viewing angle of more than +/- 30 degrees. A Gerchberg-Saxton algorithm modified with a spatial Fourier filter calculates the phase and amplitude distribution of meta-atoms. The results will open avenues to advanced eyeglasses-free 3D displays that can provide rich and well-defined depth cues.