Realizing Colorful Holographic Mimicry by Metasurfaces.

Mimicry is a biological camouflage phenomenon whereby an organism can change its shape and color to resemble another object. Herein, the idea of biological mimicry and rich degrees of freedom in metasurface designs are combined to realize holographic mimicry devices. A general mathematical method, called phase matrix transformation, to accomplish the holographic mimicry process is proposed. Based on this method, a dynamic metasurface hologram is designed, which shows an image of a "bird" in the air, and a distinct image of a "fish" when the environment is changed to oil. Furthermore, to make the mimicry behavior more generic, holographic mimicry operating at dual wavelengths is also designed and experimentally demonstrated. Moreover, the fully independent phase modulation realized by phase matrix transformation makes the working efficiency of the device relatively higher than the conventional multiwavelength holographic devices with off-axis illumination or interleaved subarrays. The work potentially opens a new research paradigm interfacing bionics with nanophotonics, which may produce novel applications for optical information encryption, virtual/augmented reality (VR/AR), and military camouflage systems.