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.

Self-bending of light in photorefractive semiconductors with hot-electron effect

Abstract: This article analyzes nonlinear light propagation in semiconductors with bipolar conductivity and nonlinear transport of electrons. We show how the competition between electron and hole conductivity can influence light propagation, leading to the self-bending effect of optical beam trajectory, which depending on the value of trap compensation coefficient may be stationary or transient.

Spatial modulation instability driven by light-enhanced nonlinearities in semiconductor CdZnTe:V crystals

Abstract: We present the experimental observation of spatial modulation instability in photorefractive semiconductor crystals (CdZnTe:V), where the optical nonlinear effects are enhanced by light. We find that the total refractive index change can be expressed as sum of a uniform index change, which can exceed the value of 0.003, and a local index change which is limited to ≈1.6×10−4. However, only the later, arising from the intensity-enhanced photorefractive effect, contributes to the formation of the modulation instability. Finally, we find that the refractive index change experiences large temporal fluctuations induced by the combination of uniform cw illumination and applied electric field.

The Electrooptic and Photorefractive Effects

Abstract: The electrooptic effect is the change in the refractive index of a material induced by the presence of a dc (or low-frequency) electric field. In some materials, the change in refractive index depends linearly on the strength of the applied electric field. This change is known as the linear electrooptic effect or Pockels effect. Linear electrooptic effect can occur only for materials that are noncentrosymmetric. Although the linear electrooptic effect can be described in terms of a second-order nonlinear susceptibility, a very different mathematical formalism has historically been used to describe the electrooptic effect. The photorefractive effect is the change in refractive index of an optical material that results from the optically induced redistribution of electrons and holes. The photorefractive effect is quite different from most of the other nonlinear-optical effects. The photorefractive effect tends to give rise to a strong optical nonlinearity. Moreover, under certain circumstances, two beams of light can interact in a photorefractive crystal in such a manner that energy is transferred from one beam to the other. This process, which is often known as two-beam coupling, can be used to amplify a weak, image-bearing signal beam by means of an intense pump beam.

Effects of transient dark currents on the buildup dynamics of refractive index changes in photorefractive polymers excited by pulsed voltage

Abstract: We study the influence of a transient dark current on the buildup dynamics of photorefractive index gratings, which are excited right after the onset of a pulsed voltage, by using low glass-transition temperature photorefractive polymers under a heat-assisted condition. We conclude that the development of photorefractive index gratings is majorly controlled by changes in the transient dark current, through the suppression of a saturated photo-induced space-charge electric field. We also show that this influence can be estimated reasonably well by a simple analysis of the measured transient current traces.