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.

Direct method for monitoring two-beam coupling in photorefractive materials

Abstract: A method for directly monitoring two-beam coupling (2BC) in photorefractive materials is presented. This method allows accurate measurement of the gain and loss in the probe and pump beams, respectively, even in situations where substantial power is diffracted into higher order beams (i.e., for large grating spacings). Modulation of the pump beam at a frequency significantly greater than the grating decay rate, coupled with synchronous detection of the modulated probe beam signal, provides this information, automatically correcting for diffractive losses. The probe beam gain and pump beam loss are obtained without further correction. 2BC measurements are made on dye-doped photorefractive polymer-supported liquid crystal films to demonstrate the advantages of this method. The measurements are made for small grating spacings, in which little high-order diffraction is observed, and for large grating spacings for which there are several diffraction orders.

Nonlinearity of the photorefractive response upon two-beam interaction in a bismuth silicon oxide crystal in an alternating electric field

Abstract: Nonlinearity of the photorefractive response is studied experimentally and theoretically upon two-beam interaction of light waves in a bismuth silicate crystal placed in an external meander electric field. The experimental data are shown to be in good agreement with a model, taking into account the influence of the second harmonic of the space-charge field on a photorefractive grating. The concentration of acceptors in a crystal and a product of the mobility of charge carriers by their recombination time are estimated from a comparison of the experimental and calculated data.

Resonant vectorial wave coupling in cubic photorefractive crystals

Abstract: We present a theory of resonant photorefractive wave coupling in cubic photorefractive crystals that are in general optically active. This theory includes the resonance enhancement of the photorefractive response in a constant applied electric field, the influence of photoelasticity, and the spatial inhomogeneity of the light intensity. In a unified manner, it allows one to describe the polarization and energy properties of two-wave coupling for the optical configurations relevant to experiment. Applications of the theory are given to photorefractive crystals of the sillenite family.

Characteristics of two-wave mixing adaptive interferometer with CdTe:Ge at 1.06 and 1.55 μm and improved temporal adaptability with temperature control.

Abstract: We have characterized a two-wave mixing adaptive interferometer based on dc-biased photorefractive CdTe:Ge crystal at 1.06 and 1.55 μm. Excellent performance is shown at both wavelengths by demonstration of high sensitivity for measurement of small displacements and high cutoff frequency at low intensity. We have achieved a considerable reduction of the undesired low-frequency response using controlled heating of the crystal, which ensures depopulation of corresponding traps. The experimental data are used for measurement of the real and imaginary parts of the coupling constant, as well as the dielectric relaxation time of the crystal and the mobility-lifetime product of the free charge carriers.

Photorefractive effects in electrooptic crystals

Abstract: The mechanisms responsible for tight-induced refractive index changes are discussed. Special emphasis is paid to the formation of space charge fields and index changes, to Bragg diffraction and selfdiffraction, to photorefractive centers and light-induced charge transport, to various possibilities of nondestructive read-out and to holographic scattering. The ability to tailor certain crystal parameters over wide ranges offers favourable perspectives for future devices.