High Refractive Index Monomers for Improving the Holographic Recording Performance of Two-Stage Photopolymers

Photopolymershold great promise for the preparationof transparentvolume holographic gratings (VHG), which are core optical elementsin many application fields. To improve the holographic recording propertyof a two-stage photopolymer, four new (meth)-acrylate monomers (CTA,CTMA, CTBA, CTBMA) with high refractive indices (1.59-1.63)are designed and synthesized in this study. Using them as one writingmonomer, a series of photopolymer samples with different formulationsand thicknesses are fabricated for holographic recording. Among them,a formulation containing 9 wt % CTMA shows the best performance. Usingit as a recording medium, a VHG with high resolution and diffractionefficiency is constructed. Its refractive index modulation reaches0.046. Moreover, its total transmittance within 400-800 nmachieves 96.62% after photobleaching. The results indicate that theCTMA-based formulation has great application potential in developinghigh-performance transparent VHG.