Based on the poly(vinyl alcohol) (PVA) system, photopolymers were prepared with two different monomers: Nvinylpyrrolidone (NVP) and acrylamide (AM). The maximum diffraction efficiency of the photopolymers was more than 85%, and the maximum sensitivity was 17.77 × 10 −3 cm 2 /mJ. The optimized photopolymer with high diffraction efficiency and high photosensitivity can achieve both the recording and reproduction of reflection holography and the recording and reproduction of transmission holography. At the same time, the effects of monomer on holographic properties of photopolymers were studied. It was found that the reactivity and migration rate of the monomer worked together on the polymerization rate, which affected the holographic properties of the photopolymer. To verify the influence of the structure of NVP and AM on the reactivity and migration rate, the transmittance and the real-time diffraction efficiency measurements were innovatively used. The NVP with high electron cloud density was more reactive, while the AM with low molecular weight and simple molecular structure had a faster migration rate.

N-vinylpyrrolidone (NVP) has a large molecular structure, so it is difficult to diffuse during holographic recording, especially at low spatial frequencies. We used glycerol to promote the diffusion of NVP, and successfully improved the holographic performance of the photopolymer at low spatial frequencies. As the concentration of glycerol increases, the holographic performance first increases and then remains stable. The optimal concentration of glycerol is 0.21 mol/L. At this concentration, the maximum diffraction efficiency of the photopolymer is 84%, the refractive index modulation is 1.95 × 10−3, and the photosensitive sensitivity is 7.91 × 10−4 cm2/mJ. Compared with the control group, the maximum diffraction efficiency, maximum refractive index modulation and photosensitivity at low spatial frequencies (800 lp/mm) have increased by 11.19 times, 4.69 times and 1.71 times, respectively. Using the optimized photopolymer for transmission holographic recording and reproduction, we have obtained a clear and bright transmission hologram. The photopolymer modified with glycerol is expected to be applied to the fields of holography, diffractive optics, and so on.

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A supramolecule photosensitizer (supra-photosensitizer) based on the host−guest complexation of cyclodextrins and a bis-chalcone dye (BDEA) was prepared. Methyl-β-cyclodextrin (Me-β-CD), with the highest inclusion rate, was confirmed as the best host among the four cyclodextrins. The host−guest properties of Me-β-CD and BDEA were characterized by FTIR, XRD, 1 H NMR, PLQY, SEM, Job's plot, Benesi− Hildebrand plot, and others. Compared to the conventional photosensitizers, the supra-photosensitizers showed higher fluorescence emission and longer fluorescence lifetime whether as a powder or distributed in a film. The improvement in fluorescence coincided with improvement in photoinitiation efficiency and was proven to enhance the generation of volume grating. It is expected that the supra-photosensitizer may open a new avenue for the design of high-performance photoinitiation systems.

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