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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TL;DR: In this paper, a photorefractive system composed of liquid crystal droplets dispersed in a photoconducting polymer is characterized by means of a two-beam coupling and the amplitudes and phases of the spatial variations of the refractive index and the absorption coefficient are measured using the moving grating technique.
Abstract: A photorefractive system composed of liquid crystal droplets dispersed in a photoconducting polymer is characterized by means of two-beam coupling. The amplitudes and phases of the spatial variations of the refractive index and the absorption coefficient are measured using the moving grating technique. Dynamic measurements indicate that the phase of the refractive index modulation is nearly constant while the amplitude increases gradually. The maximum value of the internal space charge field can be estimated from the amplitude of the phase grating and is found to be of the order of one-hundredth of the external bias field.
5 citations
TL;DR: Nonlinear behavior of the photorefractive sensitivity and photovoltaic current is found, indicating that the excitation process is connected to excitation of 4f(2) electrons of the Pr(3+) dopant through an intermediate level to the conduction band.
Abstract: The first experimental verification to the authors’ knowledge of efficient two-step recording in a photorefractive and piezoelectric crystal of La3Ga5SiO14:Pr3+ with cw laser light I<20 W/cm2 is reported. We found nonlinear behavior of the photorefractive sensitivity and photovoltaic current, indicating that the excitation process is connected to excitation of 4f2 electrons of the Pr3+ dopant through an intermediate level to the conduction band. This two-step nature of the photorefractive effect makes the crystal an exciting new candidate for applications in holographic storage.
5 citations
TL;DR: In this article, the authors exploited the nonlinearity inherent in four-wave mixing in organic photorefractive materials for adaptive filtering and demonstrated new applications which involve:======¯¯dislocation, scratches and defect enhancement.
Abstract: In prior work, we exploited the nonlinearity inherent in four-wave mixing in organic photorefractive materials for
adaptive filtering. In this paper, we extend our work further and demonstrate new applications which involve:
dislocation, scratches and defect enhancement. With the availability of the organic photorefractive materials with
large space-bandwidth product, it should open the possibility of using the adaptive filtering techniques in quality
control systems.
5 citations
TL;DR: Thermal fixing in a La(3)Ga (5)SiO (14):Pr (3+) photorefractive crystal is demonstrated all the way down to room temperature, which is the first report of such an effect in any photoreFractive material.
Abstract: Thermal fixing in a La3Ga5SiO14:Pr3+ photorefractive crystal is demonstrated all the way down to room temperature. This, to our knowledge, is the first report of such an effect in any photorefractive material. From the temperature dependence of the process the activation energy of the carriers involved in the fixing process is measured to be EA=0.89 eV.?Further, an effective photorefractive charge density of 1.4±0.2×1016 cm-3 and Debye screening length of 6.8±0.7×10-6 cm is measured.
5 citations
TL;DR: In this article, the third-order nonlinear refractive coefficient is enhanced at the edge of the photonic stop band and the photorefractive diffraction efficiency achieves a maximum value when the stop band wavelength overlaps with the laser beam wavelength.
Abstract: The variation of the refractive index is the key property of photorefractive materials and an important factor that affects photonic crystals. Therefore, photorefractive photonic crystals are interesting optical materials in physics. One of the typical groups of photorefractive materials, polymer dispersed liquid crystals (PMMA, 5CB, and C60), are filled into three dimensional silica colloidal crystals by solvent-induced phase separation to fabricate photonic crystals. The stop band shifts to shorter wavelength when a low voltage is applied. By using the z-scan and two-beam coupling technique, several band gap dependent optical properties of photorefractive photonic crystals are studied whilst continuously adjusting the wavelength of the stop band. The third-order nonlinear refractive coefficient is enhanced at the edge of the photonic stop band. The photorefractive diffraction efficiency achieves a maximum value when the stop band wavelength overlaps with the laser beam wavelength.
5 citations