Quickly updatable hologram images using photorefractive (PR) polymer composite based on poly(N-vinyl carbazole) (PVCz) is presented. PVCz is one of the pioneer materials of photoconductive polymers. PR polymer composite consists of 44 wt % of PVCz, 35 wt % of 4-azacycloheptylbenzylidene-malonitrile (7-DCST) as a nonlinear optical dye, 20 wt % of carbazolylethylpropionate (CzEPA) as a photoconductive plasticizer and 1 wt % of 2,4,7-trinitro-9-fluorenone (TNF) as a sensitizer. PR composite gives high diffraction efficiency of 68% at E = 45 V μm−1. Response speed of optical diffraction is the key parameter for real-time 3D holographic display. The key parameter for obtaining quickly updatable holographic images is to control the glass transition temperature lower enough to enhance chromophore orientation. Object image of the reflected coin surface recorded with reference beam at 532 nm (green beam) in the PR polymer composite is simultaneously reconstructed using a red probe beam at 642 nm. Instead of using a coin object, an object image produced by a computer was displayed on a spatial light modulator (SLM) and used for the hologram. The reflected object beam from an SLM was interfered with a reference beam on PR polymer composite to record a hologram and simultaneously reconstructed by a red probe beam.

We present the enhanced photorefractive performance of high molecular weight poly(N‐vinyl carbazole) (PVCz)‐based composites. Higher diffraction efficiency with faster speed of grating build‐up was obtained by optimizing the composition of the PVCz composites. At relatively low applied electric field of E = 45 V μm−1, diffraction efficiency of 26% for p‐polarized probe beam and corresponding that of 5.1% for s‐polarized probe beam were measured with faster grating build‐up speed of 48.3 s−1 for the composite with 2,4,7‐trinitrofluorenone (TNF) as a sensitizer. Fastest speed of grating build‐up of 100 s−1 and large optical gain up to 110 cm−1 were measured at E = 80 V μm−1 for the composite with fullerene derivative of PCBM as a sensitizer. These improved performances are due to a large orientational enhancement effect with faster response speed in addition to Pockels effect for the samples with appropriate glass transition temperature. © 2011 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2011

We present the optimization of poly(N-vinylcarbazole) (PVCz)-based photorefractive composite films for use in a dynamic holographic imaging system. The compositions of the composite films used in this study included PVCz/4azacycloheptylbenzylidenemalononitrile (7-DCST)/carbazoylethylpropionate (CzEPA), N-ethylcarbazole, benzyl n-butyl phthalate/ [6,6]-phenyl-C61-butyric acid methyl ester or 2,4,7-trinitro-9-fluorenone (TNF) (44/35/20/1 wt%). PVCz with molecular weights of 23 000, 100 000, 290 000, 370 000 and 810 000 g mol À1 were used. The photorefractive polymeric composite (PPC) film (PVCz with M w : 370 000/7-DCST/CzEPA/TNF, 44/35/20/1 wt%) was observed to be the most well-balanced for photorefractive performance. To demonstrate the practical application of these films, dynamic holographic images were reflected from a spatial light modulator. The optimized PPC film was used in the dynamic holographic imaging system, and well-balanced dynamic holographic images were obtained. The results from this study will contribute to the development of four-dimensional (4D À3D plus time) holographic displays.

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