Wavelength and Full‐Polarization Encrypted Orbital Angular Momentum Meta‐Holography

ABSTRACT Multiplexing multiple degrees of freedom (DoFs) of light into holography not only expands holographic channels but also enhances the encryption security. As wavelength is an essential DoF in lots of practical applications, here we successfully incorporate it into the full‐polarization encrypted orbital angular momentum (OAM) holography, to generate the wavelength and full‐polarization encrypted OAM meta‐holography realized only by a single‐layer geometric‐phase metasurface. The metasurface is designed through a straightforward process without increasing computation and structural complexity, and it fulfills the wavelength control requirements for broadband spectral response. Red, green, and blue holographic images are reconstructed at the same target plane, leveraging axial chromatic dispersion to compensate for the preset imaging distance disparity. In each wavelength channel, the superposition of right‐ and left‐circular polarization components with designed amplitude ratios and phase differences imparts the desired spatially varying polarization distribution to the reconstructed images and preserves their encoded OAM properties. In the experiment, the multiplexed meta‐holography encrypts 24 distinct images across 3 wavelengths, 12 pairs of orthogonal polarization channels, and 4 OAM channels, with expanded encoding parameter space to enhance both information capacity and encryption security. This multidimensional optical manipulation platform provides great potential for multifunctional, miniaturized, and integrated optical device applications.