Axially Separated Nonlinear Orbital Angular Momentum Holography Enabling Multidimensional Joint Addressing

Orbital angular momentum (OAM) holography provides an effective approach for multiplexed holographic information encoding. Extending OAM holography into the nonlinear optical regime further introduces additional frequency channels, enabling nonlinear OAM holography with enhanced information capacity. However, achieving independent holographic reconstruction in both the fundamental and second‐harmonic channels remains challenging. Here, we propose and experimentally demonstrate an axially separated nonlinear OAM holography scheme to address this challenge. By exploiting the intrinsic axial chromatic dispersion of a diffractive lens phase together with the nonlinear conservation of orbital angular momentum in second‐harmonic generation, holographic images encoded at the fundamental and second‐harmonic frequencies are reconstructed at distinct axial planes. The hologram is binarized and fabricated on the lithium niobate crystal using femtosecond laser direct writing. Furthermore, a spatial‐interleaving strategy is employed to realize parallel OAM multiplexing, and a hierarchical multiplexing architecture is constructed by combining spatial interleaving with spatial superposition. This approach enables multidimensional addressing in the joint space and enhances the flexibility of holographic information encoding. This work provides a versatile platform for multidimensional holographic multiplexing and offers new opportunities for high‐capacity holographic information processing and optical encryption.