The orbital angular momentum (OAM) holography has been identified as a vital approach for achieving ultrahigh-capacity multiplexation without a theoretical helical phase index limit. However, the encoding and decoding of an OAM hologram require a complete helical phase mode, which does not take full utilization of the angular space. In this paper, the partial OAM holography is proposed by dividing an OAM mode into several partial orbital angular momentums and encode each partial mode with a different target image. An image can only be reconstructed using an appropriate partial OAM mode within a specific illuminating angular range, henceforth holographic multiplexation of images can be realized. This method can significantly increase the holographic information capacity and find widespread applications.

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The orbital angular momentum (OAM) holography has been developed and experimentally demonstrated capable of holographic multiplexation and high-security encryption. However, the helical phase of an OAM mode can only be encoded into one hologram associated with a target image, and this severely limits the information capacity in practical applications. The modulated orbital angular momentum (MOAM) holography is proposed by imposing multiple modulation phase modes onto one OAM mode. Three essential properties, including the MOAMpreservation, MOAM-selectivity and MOAM-multiplexation are investigated. This method can significantly enhance the holographic information capacity and it has broad prospects for optical encryption and beam manipulations.

We present a compressive ghost-imaging encryption (GIE) scheme based on phase-shifting digital holography (PSDH). With our technique based on the PSDH, the optical information is recorded from each point of an object. Then each part of a hologram can reconstruct the original image, thus improving resolution of a reconstructed image. Using the characteristics of randomness of the PSDH, we improve security of the encryption scheme. In our simulations, a binary image is taken as a target and the mutual information, the PSDG degree and the peak signalto-noise ratio are calculated. The compressive GIE scheme based on the PSDH is compared with a pseudo-inverse algorithm based on PSDH and a common GIE scheme based on the PSDH. The simulation results demonstrate that our compressive scheme manifests better reconstruction quality, compressibility and security.