9-bit spin- and wavelength-encoded hologram using a hybrid metasurface.

Metasurface holographic encryption, with high resolution and strong concealment, is promising for information security. However, traditional metasurface holographic encryption is limited by spin-polarization channels and monochromaticity, restricting the level of security and information capacity. In this Letter, we propose a 9-bit spin- and wavelength-encoded hologram achieved by encoding phase and amplitude information into full spin polarization and primary color channels using a hybrid metasurface. Our hybrid metasurface structure can break the limitations of traditional metasurfaces, significantly increasing the number of encoded channels by an order of magnitude. We believe that this strategy can provide a new, to the best of our knowledge, approach to high-capacity information encoding and encryption.