Photorefractive Composite Based on a Monolithic Polymer

Abstract

A new class of photorefractive (PR) composite based on a fully functionalized polymer with high phase-stability is reported. The polymer containing non-linear optical (NLO) chromophores and charge-transporting carbazole moieties is synthesized by a polymer-analogous reaction. The polymer is doped with plasticizer, NLO dye, and sensitizer to fabricate the PR composite. The NLO dye is the same as the NLO chromophore moiety in the polymer side chain. The PR performance of the composite is evaluated by degenerated four-wave mixing and two-beam coupling measurements. A diffraction effi ciency of 30% at a relatively low applied electric fi eld of 45 V μ m − 1 is achieved. Despite a high concentration of NLO dye, the composites show good stability for a long period without phase separation.displays. The holograph can be recorded in a polymeric photorefractive device by two coherent laser beams, one is the object beam and the other is the reference beam and then read out by a probe beam to reproduce the holographic image. The ability to continuously record and read the hologram imparts photorefractive materials with the potential to be used in 3D communication.Required elements in photorefractive materials are charge photogeneration, a charge transporting medium, trapping sites, and non-linear optical (NLO) molecules. With a polymer, these functional properties can be combined into one material as a composite or a monolithic polymer which means a fully functionalized polymer. A typical photorefractive composite consists of a photoconductive polymer, a NLO dye, plasticizer, and sensitizer. The sensitizer is used to assist the charge photogeneration. The plasticizer is added to lower the glass transition temperature ( T g ). The primary role of the NLO dye is to provide a refractive index change in response to electric fi eld through Pockels effect. [ 2 ] The concentration of the NLO dye must be high to maximize the refractive index modulation. However, a high concentration of the highly polar NLO dye tends to induce phase separation in the relatively non-polar photoconductive polymer. In Macromol. Chem. Phys. 2012, 213, 982−988

Photorefractive response and real-time holographic application of a poly(4-(diphenylamino)benzyl acrylate)-based composite

“…Many methods that use a different chromophore or a mixture of different chromophores and a monolithic polymer have been developed. [20][21][22] A co-polymer containing triphenylamine and a small amount of the NLO chromophore in the polymer side chain will improve the compatibility between the matrix and the chromophore without reducing the polymer photoconductivity. Future work will focus on co-polymer synthesis to extend the shelf life while maintaining high PR performance.…”

Photorefractive performance of poly(triarylamine)‐Based polymer composites: An approach from the photoconductive properties

“…The polymer precipitate was collected by a centrifugation (4000 rpm, 20 min) to yield PTAA as a pale yellow powder (95.1% yield, Mw: 22,000 g mol −1 , M w / M n : 1.8, T g : 60.7 °C). Piperidinodicyanostyrene (PDCST) as a nonlinear optical (NLO) dye and (2,4,6‐trimethylphenyl)diphenylamine (TAA) as a plasticizer were synthesized using procedures described in the literature . [6,6]‐Phenyl‐C61‐butyric acid methyl ester (PCBM) (Tokyo Kasei) was used as a sensitizer.…”

Flexible All-Organic Photorefractive Devices

“…Organic photorefractive (PR) polymers have wide potential for updatable holographic imaging and dynamic holographic displays. Dynamic holography is the ultimate in three-dimensional (3D) imaging and is expected to be key technology for a next-generation display system. − Photorefractive phenomena are based on refractive index modulation derived from the distributed space-charge field through the Pockels (first-order optical nonlinearity) effect. − Since the first study of organic photorefractive polymers was reported, numerous research investigations have focused on PR polymers. − ,− …”