Improving performance of two-stage photopolymers for volume holographic recording by fluorinated epoxy-amine cross-linked matrices

Host matrices play an important role in the volume holographic gratings formation of photopolymers. In this study, a series of fluorinated epoxy resin (FTGE) with low refractive index (1.44–1.46) are synthesized and characterized by nuclear magnetic resonance spectra ( 1 H NMR, 19 F NMR) and fourier transform infrared spectra (FTIR). Fluorinated epoxy-amine cross-linked matrices are formed at room temperature and their thermal polymerization properties are investigated through real-time FTIR and thermogravimetric analyses (TGA). Using the fluorinated epoxy-amine as host matrices, holographic photopolymers are fabricated. The influence of different kinds (Prop-FTGE, Buta-FTGE, and Penta-FTGE) and weight ratios (0%, 8%, 16%, and 23%) of FTGEs on holographic performances of the photopolymers are explored. The results show that the sample with 23% Prop-FTGE has the most excellent holographic optical characteristics. 0.5 mm thick sample with 23% Prop-FTGE reaches 91% diffraction efficiency within 80 mJ/cm 2 exposure dosage, and gets a 2000 lp/mm Bragg volume grating with 0.24° angular selectivity. Meanwhile, under a single pulse exposure mode (150–200 ps pulse width, 25 mJ/cm 2 exposure dosage), a grating with 4.4% diffraction efficiency is obtained, which proves the ultrafast response and recording capability of the sample.