Advanced encryption method realized by secret shared phase encoding scheme using a multi-wavelength metasurface

Multi-channel information encryption technology has been implemented by optical metasurfaces owing to their superior ability to control the phase, amplitude, wavelength and polarization of incident light. However, current metasurface-based multi-channel encryption technologies suffer from information leakage in non-full channel decoding processes. To better increase the security of the encrypted information, we develop a secret shared phase encoding scheme by combining a visual secret sharing scheme with a metasurface-based phase-encoding technique. Our method achieves its high-concealment through mapping the target image into a set of unrecognizable phase-only keys that are subsequently encoded by a multi-wavelength metasurface. In the decryption process, the secret information can be reconstructed only by decoding and stacking all the wavelength channels of the metasurface. At the same time, chaotic images can be extracted from the other channels without revealing any original information. The simulated results and the theoretical analysis show the strong robustness and high security of our encryption setup, which is sure to find applications in emerging optical encryption schemes.