Organic photorefractive materials

About: Organic photorefractive materials is a research topic. Over the lifetime, 697 publications have been published within this topic receiving 13041 citations.

Photorefractive running hologram for materials characterization

Abstract: We report a theoretical model for a photorefractive running hologram in bulk-absorbing materials in the presence of self-diffraction and use this model to analyze experiments for photorefractive materials characterization. A nonperturbative technique that allows one to measure at the same time the diffraction efficiency and the output beam’s phase shift is reported, and its advantages are discussed. We use this technique and apply the theoretical model to compute some parameters for the electron-charge carriers (Debye screening length ls≈0.03 µm, diffusion length LD≈0.14 µm, and photoexcitation quantum efficiency Φ≈0.45) at the 514.5-nm-wavelength laser line for a nominally undoped Bi12TiO20 crystal. Particular experimental features are detected and assumed to be consequences of hole–electron competition in this sample.

Diffraction cancellation over multiple wavelengths in photorefractive dipolar glasses.

Abstract: We report the simultaneous diffraction cancellation for beams of different wavelengths in out-of-equilibrium dipolar glass. The effect is supported by the photorefractive diffusive nonlinearity and scale-free optics, and can find application in imaging and microscopy.

Optical dispersion of the refractive index modulation in low Tg photorefractive polymers

Abstract: We measure at different wavelengths the linear and nonlinear optical properties of a new chromophore for photorefractive applications by means of frequency-dependent ellipsometry experiments. We show that the optical dispersion of the refractive index modulation responsible for the high diffraction efficiency in low Tg polymers can be described by a two-level model.

Effect of the chromophore donor group and ferrocene doping on the dynamic range, gain, and phase shift in photorefractive polymers

Abstract: We have studied the photorefractive performance of poly(N-vinylcarbazole)-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 >130 cm−1 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 Effect in a Polymer Molecularly Doped with Low-Molecular-Weight Compounds

Abstract: The photorefractive effect is observed in poly (methylmethacrylate) molecularly doped with three types of low-molecular-weight compounds, carrier transport (CTM), carrier generation (CGM) and nonlinear optical (NLO) materials. With these materials as dopants, the polymer exhibits both photoconductivity and the electro-optic (EO) effect under DC electric fields. The EO coefficient r33 is found to be linearly dependent on applied fields because of the lower glass-transition temperature (T g). In two-beam coupling and diffraction measurements, refraction gratings are written in the polymer. A phase shift of 90° between a refraction grating and a fringe pattern with applied fields proves the existence of the photorefractive effect, which is distinguished from heating effects. A maximum diffraction efficiency η of 4×10-6 is obtained in the photorefractive polymers.