The polarization self-modulation effect was applied for effective measurement of the characteristic response time of nominally pure Bi(12)SiO(20) (BSO) at wavelengths of 810 and 980 nm. Owing to oxygen deficiency in the crystal lattice, the BSO crystals showed unusual photorefractive sensitivity and remarkable operation speed in the near-infrared spectral region. A response time of 130 ms was measured at 810 nm, and a response time of 540 ms was measured at 980 nm, with incident intensities of 110 and 200mW/cm(2), respectively. To our knowledge, this is the first experimental evidence of a subsecond response in the infrared for a nonsemiconductor photorefractive material.
We proposed and experimentally studied a technique of vibration object monitoring. The technique is based on self-diffraction of the speckle pattern on the adaptive correlation filter recorded in photorefractive Bi12TiO20 crystal. This filter is recorded owing to the light-induced scattering known as fanning effect. The proposed technique is as sensitive as interferometric systems and it is very simple for implementation: neither reference nor readout beam is needed for operation. It is shown that the system has a linear response on the lateral displacement of the object surface and its dynamic range can be easily varied depending on experimental conditions.
We experimentally observed the self-channeling of the light beam in photorefractive Bi12TiO20 fiberlike sample owing to the strong fanning effect. It results in significant speed up of the photorefractive response time in waveguides and in anomalous dependence of the response time on the applied ac electric field amplitude: the higher electric field, the faster response.
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