基于单层基板双面液晶偏振体光栅的大视场角光波导AR显示OA

Cross type liquid crystal polarization volume grating(PVG)-based two-dimensional pupil expansion waveguides have emerged as a research hotspot in AR displays due to their compact structure and fabrication simplicity(no dynamic adjustment of interference angles is required during holographic exposure);however,their field of view(FOV)for AR applications is constrained by traditional dual-waveguide stacking approaches.To enhance the FOV,this work proposes an optical waveguide architecture based on a single-layer high-refractive-index glass substrate(n=1.9)coated with left-handed and right-handed PVGs on both surfaces,where the horizontal azimuthal angles of the reciprocal lattice vectors for the input-coupler and output-coupler gratings are 0° and 60°,respectively.Incident light is split into two separate total internal reflection paths via PVG polarization selectivity;partial out-coupling occurs when the combined reciprocal lattice vector provided by the input and output gratings sums to zero,forming a complete two-dimensional expanded exit pupil.Based on the grating diffraction equation and substrate refractive index,we derived the required PVG period for the central FOV aligned with the waveguide normal direction.In addition,the input-coupling mechanism for vertically incident 532 nm collimated light is validated via COMSOL simulations.The fabricated prototype(28 mm×22 mm output grating)achieved a 32.8°(horizontal)×18.7°(vertical)FOV(37.8° diagonal),representing a 26%improvement in the diagonal FOV over prior work.This design eliminates traditional bonding processes by direct dual-side PVG fabrication,circumventing stringent requirements for index-matching adhesives/substrates,significantly simplifying fabrication process and reducing costs.The high-refractive-index substrate further increases FOV while enhancing image quality,providing a promising high-performance solution for AR near-eye displays.