Topic
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.
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10 Sep 2000
TL;DR: In this paper, a waveguide is fabricated by the technique of ion-beam implantation in a BaTiO/sub 3/:Rh substrate, and the characteristics of the photorefractive effect are studied via two-beam coupling experiments.
Abstract: Summary form only given At the infrared wavelengths, a few studies have been dedicated to the photorefractive properties of waveguides fabricated with oxide ferroelectric crystals For the first time, a waveguide is fabricated by the technique of ion-beam implantation in a BaTiO/sub 3/:Rh substrate The characteristics of the photorefractive effect are studied via two-beam coupling experiments
18 May 1997
TL;DR: In this article, the authors proposed a new class of organic photorefractive materials: polymer dispersed liquid crystals (PDLC), which combine the high resolution of polymers, and the high refractive index changes associated with field-induced reorientation of nematic liquid crystals.
Abstract: Organic photorefractive materials’ have attracted a lot of attention in recent years because of their high performance and great potential in photonic applications, including holographic storage, optical correlation,’ dynamic holography, image processing, nondestructive testing, novelty filtering, and phase conjugation. Photorefractive polymers look particularly promising because of their high efficien~y,~ low cost, and ability to be processed into large area films. In recent years, polymers have reached a level of performance where they compete with inorganic photorefractive crystals. High refractive index modulation amplitudes (An = 7 X have been demonstrated3 in low glass transition temperature polymers as a result of orientational effects. However, the high electric field needed to pole the chromophores is a limitation. To reduce that field, photorefractive nematic liquid crystals have been proposed and demon~trated.4.~ In these materials, an internal spacecharge field reorients the director of the nematic liquid crystalline phase. However, the macroscopic coherence length of the nematic liquid crystalline phase limits the resolution of these materials and high efficiency is observed only for large values of the grating spacing (A >10 pm). Here, we present a new class of organic photorefractive materials: polymer dispersed liquid crystals (PDLC). These new materials combine the high resolution of photorefractive polymers, and the high refractive index changes associated with field-induced reorientation of nematic liquid crystals. We demonstrate that high refractive index modulation amplitudes can be achieved at lower applied field. Such materials are prepared by dispersing liquid crystal droplets of almost spherical shape in a photoconducting solid organic polymer matrix. The sensitizing, photoconducting, and trapping properties necessary for the buildup of a space-charge field are provided by the polymer matrix and the refractive index changes are due to the field-induced reorientation of the liquid crystal droplets as illustrated in Fig. l. For our experiments, we
14 Sep 1998
TL;DR: In this paper, the power conversion factor of a ring resonator is defined as the ratio of the resonating beam intensity to the intensity of the external pump beam, which is a function of the type of photorefractive material.
Abstract: Numerous interaction geometries have been developed for photorefractive materials that rely on amplification of light via the two-beam coupling effect. One of the most elegant and simple configurations is a unidirectional ring resonator, which consists of a photorefractive crystal placed in a ring cavity and pumped by an external beam. If the two-beam coupling gain is above threshold, the resonating beam will build up from the amplification of scattered light. We present results on the most crucial parameters for the effective build-up of power in the resonating beam the wavelength of the pump beam, and the type of photorefractive material. The resonating beam accumulates energy from successive amplification in a photorefractive material until saturation sets in but also loses energy from absorption and other losses such as Fresnel reflections from the crystal and imperfect mirrors. We have performed intensity-dependent modelling of the resonator's power conversion factor. The power conversion factor is defined as the ratio of the resonating beam intensity to the intensity of the external pump beam. The figure below shows the dependence of this factor on absorption coefficient for different values of coupling coefficient Gamma.
30 Aug 2005
TL;DR: In this paper, the photorefractive properties in barium titanate crystal are associated with the concentration variation, and the change of the shallow concentration can be estimated through the light-induced absoption, but the relation between oxygen partial pressure also.
Abstract: In this report, the photorefractive properties in barium titanate() crystal are associated with the concentration variation. Not only the change of the shallow concentration can be estimated through the light-induced absoption, but the relation between oxygen partial pressure also. A correlation between measurement of photoconductivity and light-induced absorption yields the concentration variation is a function of oxygen partial pressure. Otherwise, the wavelength dependent photorefractive properties of the are investigated and discussed.
16 Jun 2015
TL;DR: In this article, the temporal dynamics of the Sn2P2S6 sample transmission were studied to reveal a sequence of processes that result in a desirable sensitization, and the effect of pre-exposure to visible light on the photorefractive response was investigated.
Abstract: : Pre-exposure of Sn2P2S6 to visible light gives rise to a temporary increase of the effective trap density and thereforeimproves the photorefractive response. With cw pre-exposure and nanosecond pulse pre-exposure we study temporal dynamics of the Sn2P2S6 sample transmission to reveal a sequence of processes that result in a desirable sensitization.