Nonstationary amplification of holographic gratings in birefringent photorefractive crystals

A theoretical model of nonstationary self-amplification of weak holographic gratings in birefringent photorefractive crystals with two-and one-frequency readout is presented. The model takes account of the multiwave and vector character of the interactions and the simultaneous occurrence of intra-and intermode recording and diffraction processes with different phase detunings and complex coupling constants, which take account of the local and nonlocal response mechanisms of the medium. Analytical solutions are obtained for the intercoupled recording and diffraction equations. The results of numerical calculations of the kinetics of the spatial amplitude-phase profile and gain of the holographic grating and the selective amplification properties with intra-and intermode interaction geometries are presented. Zh. Tekh. Fiz. 67, 68–77 (April 1997)     

Quasicollinear acoustooptical interaction in three-dimensionally optically inhomogeneous crystals

A theoretical model is given for the quasicollinear acoustooptical interaction of beams in a three-dimensionally optically inhomogeneous, anisotropic medium. Analytical solutions of the coupled wave equations are obtained for a regular linear inhomogeneity model in relation to the spatial profiles of the frequency spectrum of the diffracted field. The spatiospectral transfer functions are determined, and their selective properties are investigated for various orientations and magnitudes of the gradient of the optical inhomogeneity for both low and high diffraction efficiencies. Numerical simulation results are given.Tomsk State Academy of Control Systems and Radioelectronics. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 7, pp. 91–104, July, 1995.     

Diffraction characteristics of acoustooptic interaction in an acoustic field with a curved wave front

A theoretical model is presented for the strong two-dimensional acoustooptic interaction (AOI) of finite-size beams with arbitrary profiles in an acoustic field with a curved wave front. Transfer functions are derived in a universal normalized form for the AOI. The results of numerical simulation of the diffraction characteristics show that during AOI in an acoustic field with a curved wave front the product of the diffraction efficiency and bandwidth increases at least 1.5 times for a weak interaction and more than five times for a strong interaction. The optimal values of the normalized parameters (of the acoustooptic coupling and the curvature), for which the efficiency and bandwidth are maximum, are determined.Tomsk State Academy of Control Systems and Electronics. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 4, pp. 41–50, April, 1995.     

Dynamics of optical self-amplification of holograms in photopolymeric materials

The proposed theoretical model describes the dynamic optical self-amplification of holograms in amorphous photopolymeric materials with photopolymerization and diffusion. Analytic solutions of the cross-coupled writing and diffraction equations are obtained. Computer-modeling results are used to analyze kinetic aspects of hologram optical amplification, the transformation of the amplitude-phase field of the holographic gratings in space and time, and the evolution of the spectrum-angular sensitivity of the amplification process. Tomsk State Academy of Control Systems and Radioelectronics. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 1, pp. 81–91, January, 1997.     

Diffraction characteristics of the PDLC photonic structures under the influence of alternating electric fields

The effect control voltage polarity has on the diffraction characteristics of photonic structures formed in polymer dispersed liquid crystals (PDLCs) is discussed. The possibility of controlling these characteristics with an alternating electric field is demonstrated.     

Diffraction of light beams by damped ultrasonic waves in gyrotropic cubic crystals

The diffraction of light beams by ultrasound with a two-dimensionally nonuniform, exponentially damped amplitude distribution in gyrotropic cubic crystals is investigated theoretically. An analytical model of strong acoustooptic interaction is constructed on the basis of self-consistent solutions of the vector-matrix partial differential equations for coupled waves written in the amplitudes of the light beam. The model can be used to determine the spatial profiles of the intensity and the polarization structure of the diffracted field for arbitrary diffraction efficiencies and geometries. Numerical simulation results are given.State Academy of Control Systems and Radio Electronics, Tomsk. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 2, pp. 8–19, February, 1995.     

Dynamic Light Diffraction by Holographic Gratings in Photopolymeric Materials

A theoretical model of light diffraction by tilted holographic gratings in photopolymeric materials in the nonstationary regime of reading, which describes the dynamic process of optical hologram amplification with allowance for the photopolymerization and diffusion mechanisms of recording, is developed. For the given model, the dynamics of the diffraction efficiency and selective properties of hologram reading are modeled numerically when Bragg's conditions are satisfied and violated. It is demonstrated that the diffraction characteristics of tilted holograms are spatially noninvariant for the reading beam direction. The optimal conditions of reading of tilted holograms are established.     

Analytical model of light beam diffraction by one-dimensional electrically controlled non-uniform transmission photon PDLC structures

A mathematical model describing two-dimensional diffraction of quasi-monochromatic light beams by onedimensional electrically controlled non-uniform holographic photon structures in photopolymer dispersed liquid crystal (PDLC) materials is presented. The model describes light field distributions in the near and far field zones with allowance for the refractive index profile in the structure, light beam divergence, and encapsulation of liquid crystal molecules.