Larionova E. Polarized and spatio-temporal transformations of light beams in the AgCl-Ag films

Object of study: thin photosensitive AgCl-Ag films. Aim: to study the nature of nonlinear optical phenomena that occur at the interaction of light with the AgCl-Ag films, i.e. photoinduced dichroism (PD) and transformation of light polarization by dichroic samples, spontaneous periodic structure (PS) and spatio-temporal transformations of laser beams during the process of the PS formation. Methods: The films were prepared by the method of thermal vacuum evaporation. Their thicknesses were measured by the diffraction method with the aid of the PS. The PD was studied by the polarimetric method. The polarization and the spectral decomposition of light in the dichroic samples were observed visually and registered photographically. The dynamic patterns of scattering and diffraction were observed visually, registered by photographic and photo-electric methods. The periods of the PS were measured by the diffractometer method. Results, novelty: It has been shown that the plane-of-polarization rotation in the continuous visible spectrum registered with the PD and the PS in the AgCl-Ag films is reconstructed due to the polarization and spectral transformations of the white light beam in the dichroic sample or because of the azimuthal rotation of diffracted beams and the small-angle scattering in the samples. The PS first has been obtained in the AgCl-Ag films under the action of a polychromatic inducing beam. It has been shown that under identical conditions of spatial scattering of modes with different frequencies in the film the PS develops only on single mode having maximum Q-factor due to effect of the positive feedback. The formation of holographic gratings and the emergence of the self-diffraction effect first have been revealed at their development in the AgCl-Ag films on the ZnS plate surface irradiated by a single laser beam at off-normal incidence. The non-linear effects of optical turbulence and spatio-temporal evolution in the small-angle scattering bands and in the diffraction reflexes have been revealed and discussed under the action of the focused Gaussian linearly polarized laser beam at the normal and off-normal incidence for the first time. Field of implementation: nonlinear optics, polarized holography, scientific photography, optics of nonlinear planar waveguides.