Dual-Parameter Encoded Orbital Angular Momentum Mode Multiplexing Holography Using Rotatable Diffractive Neural Networks

Orbital angular momentum (OAM) mode multiplexing holography holds significant potential for high-capacity optical display and high-security data encryption. However, current mode multiplexing holography faces challenges in the expanding and switching of holographic channels due to the finite dimensionality of optical multiplexing parameters and the fixed mode-to-hologram mappings. To overcome these limitations, we present a dual-parameter encoded OAM mode multiplexing holography approach, which introduces rotation states as an extrinsic modulation degree of freedom via rotatable diffractive neural networks (R-DNNs) beyond intrinsic OAM modes. This framework enables a one-to-many mapping between a single OAM mode and multiple distinct holograms, allowing for information encoding across multi-dimensional spaces and extending holographic channel capacity. By combining 4 OAM modes with a three-layer R-DNN supporting 4 rotation states, we achieved a 16-channel multiplexed holographic system. Additionally, we demonstrated an optical image encryption scheme utilizing segmentation mapping, achieving high-fidelity encryption of a floral pattern by exploiting the diverse mappings between modes and rotation states. This work introduces a novel method for enhancing OAM holography capacity, confirming the feasibility of non-optical parametric encoding for multiplexing holography.