Recording Reflection Volume Holographic Gratings with Enhanced Performance by Two-Stage Photopolymers Containing Bifunctional Monomers

Abstract

A holographic optical waveguide (HOW) is an optimal solution for augmented reality (AR) displays, in which reflection volume holographic gratings are core optical elements. In this study, five high-refractive-index (≈1.6) bifunctional acrylate monomers (TPBSAs) are designed and synthesized. A series of two-stage photopolymers are prepared using TPBSAs as writing monomers. Among them, one containing 9 wt.% TPBSA-3 shows the best holographic recording performance with a sensitivity as high as 26.59 cm mJ⁻¹. Using it as the recording medium, a reflection VHG can be obtained with high spatial frequency (5634 lines per mm), diffraction efficiency (97.14%), refractive index modulation (0.029), and good transparency within 400−800 nm after photobleaching. Furthermore, a HOW capable of achieving virtual and real image fusion is fabricated.