  Metasurface holography has the advantage of realizing complex wavefront
modulation by thin layers together with the progressive technique of
computer-generated holographic imaging. Despite the well-known light
parameters, like amplitude, phase, polarization and frequency, the orbital
angular momentum (OAM) of a beam can be regarded as another degree of freedom.
Here, we propose and demonstrate orbital angular momentum multiplexing at
different polarization channels using a birefringent metasurface for
holographic encryption. The OAM selective holographic information can only be
reconstructed with the exact topological charge and a specific polarization
state. By using an incident beam with different topological charges as erasers,
we mimic a super-resolution case for the reconstructed image, in analogy to the
well-known STED technique in microscopy. The combination of multiple
polarization channels together with the orbital angular momentum selectivity
provides a higher security level for holographic encryption. Such a technique
can be applied for beam shaping, optical camouflage, data storage, and dynamic
displays.
