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.

Measurement of the photorefractive space-charge field in a ferroelectric mesogen

Abstract: We report on the measurement of the photorefractive space-charge field in a chiral smectic C mesophase. The liquid crystal is intrinsically photoconducting and undoped. The space-charge field amplitude, obtained from a model connecting the induced refractive index modulation with the electric fields within the medium, is only 1% of the applied field. Nonetheless, high refractive index modulations Δn∼10−3 can be obtained because of the high spontaneous birefringence of the mesophase. The use of the standard models for inorganic crystalline photorefractive materials would have given a space-charge field amplitude two orders of magnitude higher.

Simultaneous observation of photobleaching and photorefractive effects in germanium-doped optical fibers

Abstract: Photobleaching and photorefractive effects caused by intense pulsed laser irradiation at 532 nm have been observed simultaneously in a germanium-doped monomode fiber. A decrease of up to 4.1*10/sup -4/ in the refractive index of the core at 633 nm was inferred from the change in the radiation pattern of a probe beam and also from the change in the cutoff wavelength of the LP/sub 11/ mode. The effect is attributed to the bleaching of preexisting Ge(1) color centers in the fiber. >

Modes of photorefractive surface waves

Abstract: We consider the modes of surface waves with the diffusion mechanism by the band transport model of the photorefractive effect and the nonlinear equation for the first time. We demonstrate the relationship between the modes of surface waves and the angles of incidence. The conditions for the realization of surface modes at the interface between photorefractive crystal and a metal, a linear dielectric with a lower refractive index, or another photorefractive crystal are discussed.

Z-scan measurements of photorefractive nonlinearities for a SBN: Ce crystal

Abstract: In this paper, we derived the Z-scan formula for a photorefractive crystal sample under an external applied electric field. The far-field diffraction pattern of a Gaussian beam wavefront through a photorefractive crystal is calculated by considering spatial-phase perturbation induced by the space-charge field. The photorefractive drift nonlinearities and correspondingly, the electro-optic coefficients r 33, r 13, (r 23) and the characteristic ratio n 3 e r 33/n 3 o r 13 for a cerium-doped Sr0.61Ba0.39Nb2O6 crystal are determined from the Z-scan experiments. Z-scan with enhanced sensitivity is also realized by measuring the normalized transmittance at the off-axis position in the far field. A deviation between the off-axis Z-scan experimental results and the theoretical prediction is discussed too.

Photorefractive imaging of semiconductor wafers

Abstract: Making use of the photorefractive effect, we have developed a versatile method of imaging various crystal properties of semi‐insulating compound semiconductors. The magnitude and time evolution of refractive index gratings are monitored via diffraction. The observed diffraction is directly related to the electric fields present, and quantitative information concerning the spatial variation of dark conductivity, photoconductivity, and deep level absorption can be extracted. Wafers of undoped GaAs and InP:Fe have been characterized in this manner, and comparisons of images are made which demonstrate the capabilities of this technique.