Polymer-dispersed liquid crystal (PDLC) gratings, as an emerging optical material, have significant advantages such as low fabrication cost, suitability for large-area processing, and rapid electro-optic response. They show great potential in holographic waveguide displays and optical interconnection systems, where they are often used as key beam-splitting and coupling components. However, most of current beam-splitting devices based on PDLC materials are limited to generating 2×2 diffraction arrays, which greatly restricts their ability to achieve multi-channel and multi-order light field modulation, thereby failing to meet the growing demands for high-dimensional optical information processing.

To overcome this limitation, this study proposes a fabrication scheme for two-dimensional PDLC gratings based on holographic multi-beam interference. First, starting from holographic interference theory, we rigorously derive the light intensity distribution function of the multi-beam interference field. Second, a physical model of a volume holographic transmission grating with a refractive index distribution matching the interference field intensity is constructed using the finite element analysis software COMSOL Multiphysics. Utilizing this model, we simulate and optimize the final diffraction performance by changing key fabrication parameters, such as the exposure intensity ratio between the reference and object beams and the grating layer thickness.

During the experimental validation phase, we successfully fabricate a one-dimensional PDLC grating by using a symmetrical three-wave interference exposure method. Under normal incidence with a 532 nm laser, the fabricated one-dimensional PDLC grating exhibits symmetric diffraction, with both first-order beams showing a diffraction efficiency exceeding 44%, thereby preliminarily verifying the reliability of the model. On this basis, we further design an innovative five-wave interference exposure setup. Using a custom-made quadrilateral pyramid beam splitter, we achieve five-beam interference and successfully prepare a two-dimensional PDLC grating that meets the design specifications. The test results demonstrate that under normal incidence at 532 nm, this two-dimensional grating produces a 3×3 two-dimensional diffraction array. The 1st-order diffraction angle is 18.4°, and the beam-splitting energy ratio of each single 1st-order diffracted light exceeds 10%, achieving efficient energy distribution.