Orbital angular momentum multiplexing holography based on multi-plane light conversion

Orbital angular momentum (OAM), with its unique orthogonality, is widely applied in optical holographic encryption and information storage. Theoretically, the topological charge of OAM holography is infinite. However, in practice, it is restricted by the Nyquist-Shannon sampling theorem and experimental equipment, resulting in a relatively small number of practically usable channels. We propose an OAM holography technique based on multi-plane light conversion (MPLC) to increase the number of multiplexed channels in OAM holography. In contrast to conventional OAM holographic designs, the present design employs a limited number of phase planes to achieve multi-channel coaxial OAM multiplexing holograms. In the experiment, we using four MPLC phase planes to reconstruct six coaxial OAM holograms, the peak signal-to-noise ratio (PSNR) value of the reconstructed holograms exceeds 20 dB, and the crosstalk between multiple modes is less than -19 dB. This mitigates the crosstalk problem of multiple images and provides what we believe to be a new way to realize large-capacity and high-quality optical holography encryption and information storage.