Iuri Mshvenieradze

Dynamic polarization-holographic gratings with a different profile of anisotropy in the band are presented. Polarization-sensitive recording materials of two types are used: material possessing high dark relaxation and highly reversible material without dark relaxation in which the recorded grating is erased by a circularly polarized beam. For a grating recorded by two orthogonally circularly polarized beams a diffraction efficiency of 20% has been obtained at 3.5 W∕cm2 power density during 1 ms recording/erasing time. An all-optical cross commutator based on the matrix of dynamic reprogrammable polarization-holographic microholograms is considered. The amplification of the weak beam at two-wave mixing in polarization-sensitive materials has been shown, with an obtained amplification coefficient of 4.95

The phenomenon of vector photochromism was observed in some high-efficient polarization-sensitive materials depending on the radiant exposure of the inducing linearly polarized actinic light. The phenomenon has the purely vector nature because the absorption of the irradiated and unirradiated areas of the material is practically identical when we use unpolarized probing light. However, an essential change in the absorption spectrum was observed under probing the sample by linearly polarized nonactinic light when it passes through an analyzer, and this change depends on the value of radiant exposure. The kinetics of the photoanisotropy induced by linearly polarized actinic light at 457 nm was studied in case of wavelengths of 532 and 635 nm of the probing beam. The noticeable difference in absorbance was observed with increase in radiant exposure from 60 J∕cm2 up to 250 J∕cm2 for the used wavelengths of the probing beam. The experimental results obtained in polarization-sensitive material based on the ammonium salt of the azodye Mordant pure yellow in a gelatin matrix are presented. The dependence of the effective anisotropy on the material thickness has been investigated. The mechanism of the phenomenon is discussed. The observed effect can be used for creating dynamic polarization spectral filters controlled by light and the spectrally selective dynamic polarization holographic gratings

A new method for determining the distribution of birefringence and linear dichroism in optical polymer materials is presented. The method is based on the use of polarizationholographic diffraction grating that forms an orthogonal circular basis in the process of diffraction of probing laser beam on the grating. The intensities ratio of the orders of diffraction on this grating enables the value of birefringence and linear dichroism in the sample to be determined. The distribution of birefringence in the sample is determined by scanning with a circularly polarized beam with a wavelength far from the absorption band of the material. If the scanning is carried out by probing beam with the wavelength near to a maximum of the absorption band of the chromophore then the distribution of linear dichroism can be determined. An appropriate theoretical model of this method is presented. A laboratory setup was created for the proposed method. An optical scheme of the laboratory setup is presented. The results of measurement in polymer films with two-dimensional gradient distribution of birefringence and linear dichroism are discussed.

We have developed a technology for obtaining polarization-holographic gratings (the gratings have anisotropic profile continuously changing within each spatial period) with different distribution of anisotropy in the grating period, as well as the technology for obtaining polarization-holographic elements based on such gratings. To obtain gratings and elements, special high-performance polarization-sensitive materials developed by us are used. We can present samples of gratings and elements and demonstrate how they work. We have developed the technology of obtaining of polarization-holographic gratings that have anisotropic profile continuously changing within each spatial period and also the technology of reception of polarization-holographic elements on the basis of such gratings. Special highly effective polarization-sensitive materials developed by us are used for obtaining such gratings and elements. We can present samples of gratings and elements and give a demonstration of their work.

Phenomenon of vector polyphotochromism was observed in some high-efficient polarization-sensitive materials dependent on the radiant exposure when material was illuminated with linearly polarized actinic light. The phenomenon has purely vector nature, since under probing by unpolarized light, the transmission spectra of the irradiated and unirradiated area of the material are practically identical. However, an essential change in the transmission spectrum of the material was observed by placing the irradiated area between crossed polarizers when the orientation of the axis of induced anisotropy was of 45 degrees relative to the axes of the polarizers. The dispersion of photoanisotropy was studied at different exposure values. Kinetic curves of the photoanisotropy were obtained for wavelength of 532 nm and 635 nm of probing beam for different values of exposure (30, 60 and 250 J/cm2 ) with linearly polarized actinic light (457 nm). The dispersion curves of the photoanisotropy were obtained for these values of exposure showing an anomalous behavior for exposures above of 30 J/cm2 . This phenomenon was observed in specially synthesized organic materials based on azo dyes introduced in a polymer matrix. The difference between optical densities was obtained for polarized light with a wavelength of 532 nm and 635 nm at different exposures, which makes the prospect the dynamic polarization spectral filters controlled by light and the spectrally selective dynamic polarization holographic gratings to be created.

A new method is presented for determining the distribution of birefringence and linear dichroism in different materials based on the polarization-holographic element when circularly polarized light beam transmitted through the sample diffracts on the element.