Photorefractive properties and applications of polymer composites and fully functionalized polymethacrylates (original) (raw)
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Fully Functionalized Photorefractive Polymethacrylates with Net Gain at 780 nm
Macromolecules, 2000
We report on the synthesis and characterization of three fully functionalized photorefractive polymethacrylates containing different chromophores. Carbazole-and NLO-functionalized methacrylate monomers in a 1:1 ratio were polymerized with 20 mol % of dodecyl methacrylate to obtain photorefractive polymers. The resulting polymers had glass transition temperatures of 48, 47, and 52°C, respectively. Asymmetric two-beam-coupling and four-wave-mixing experiments at 780 nm and three different temperatures pointed out that the resulting polymers, doped with 1 wt % (2,4,7-trinitro-9-fluorenylidene)malononitrile (TNFDM), showed good photorefractive properties. A net two-beam coupling gain and a diffraction efficiency of 60% were observed at 58 V/µm. 10.
Organic Electronics - ORG ELECTRON, 2009
Photoconductivity and birefringence are two important factors that affect performances of photorefractive devices. Here, the optical properties of this composite based on copoly[6,6′-bis(9-(2-ethylhexyl)carbazole-3-yl)/thieno-(2,5-b)thiophenylidenevinylene] as photoconducting material, 2-[3-[(E)-2(piperidine)-1-ethenyl]-5,5-dimethyl]-2-cyclohexenyliden]malononitrile as nonlinear optical chromophore, butyl benzyl phthalate as plasticizer and C60 as photosensitizer, has been compared to those of the corresponding non-π-conjugated polymer composite. The 50-μm thick photorefractive composite showed a diffraction efficiency 37.2% at 50V/μm, which corresponded to a Δn of 2.62×10−3. When we compare the speeds of the current and the non-conjugated analogue composites, the current composite has about a factor of seven larger speeds due to the π-conjugated polymer backbone. We also discuss and present simple explanation of the observed effect.
The Journal of Chemical Physics, 2000
We have studied the photorefractive performance of poly͑N-vinylcarbazole͒-based composites doped with various concentrations of two structurally related dipolar chromophores, at 780 nm. The two chromophores had different electron donor groups, N,N-diethylamine and julolidine, respectively. Complete internal diffraction and gain coefficients Ͼ130 cm Ϫ1 were obtained for polymers doped with these chromophores. The polymers prepared with the chromophore having the strongest electron donor group, the julolidine group, had the largest dynamic range, but proved to be slower and had a smaller photorefractive phase shift.
Photorefractive behaviors in a polymer composite including layered silicates
Applied Clay Science, 2002
Photorefractive (PR) behavior was observed in a polymer nanocomposite system. The composite is made up of poly(Nvinylcarbazole) (PVK), 2,4,7-trinitro-9-fluorenone (TNF), 4-(4-nitrophenylazo)aniline (DO3), and 9-ethylcarbazole (ECZ), with or without Montmorillonite (MMT) or laponite as a layered silicate. The structures of nanocomposite-PR samples were investigated by X-ray diffraction (XRD). To investigate the PR property, two-beam coupling (TBC) and four-wave mixing experiments were performed. The gain coefficients of the MMT-based nanocomposite-PR system are somewhat lower than that of the unfilled system. However, the equilibrium normalized final diffracted signal of PR-nanocomposite is higher than the unfilled PR sample. Furthermore, by adding laponite instead of MMT to the polymeric PR system, the gain coefficient increases to the original value of the unfilled system by reducing the light scattering, so that it can be said that the memory stability is greatly enhanced in grating decay behavior.
Efficient Functionalized Photorefractive Polymers with Infrared Sensitivity
The Journal of Physical Chemistry B, 2002
We have prepared new photorefractive methacrylate copolymers functionalized with a highly polar bifunctional chromophore. The photorefractive response was studied by ellipsometry, four-wave mixing, and two-beam coupling and is compared to that of polymers and polymer composites studied previously. The polymer could be sensitized with C 60 for operation at the writing wavelength of 780 nm, which results in an improved grating build-up time. At this wavelength, we have observed overmodulation of the internal diffraction efficiency at an applied bias field of 43 V/µm. We have found evidence for the formation of aggregates and phase separation in the copolymers.
High net gain at 514 nm in a photorefractive polymer doped with a chalcone derivative
Applied Physics Letters, 1997
We report on the photorefractive properties of a low T g composite consisting of functionalized polysiloxane doped with a chalcone derivative. The high transparency of this doping molecule enabled the observation of high net gain at 514 nm. Orientational and Pockels contributions to the total refractive index variations were measured by frequency-dependent ellipsometry experiments. Finally, the field dependence of the gain coefficient is described using Kukhtarev's model for the space charge field with an effective trap density as a single fitting parameter. © 1997 American Institute of Physics. ͓S0003-6951͑97͒03340-8͔
Photoconducting polymers for photorefractive nonlinear optics
1994
Photoconducting polymers doped with nonlinear optical molecules show important photorefractive properties. These new polymer composites are promising materials for photonic applications such as dynamic holographic storage and image processing. The photorefractive properties of a highly efficient polymer composite based on poly("vinylcarbazole) are investigated and discussed.