Expressions For Diffraction Efficiency Research Articles

Orientational photorefractive holograms in porphyrin:Zn-doped nematic liquid crystals

We investigated the diffraction properties of dynamic holograms recorded in porphyrin:Zn doped nematic liquid crystals (NLCs) under the influence of an applied dc electric field for various conditions of the grating period, the writing beam intensity and the applied electric field. We also derived an analytic expression for diffraction efficiency from NLCs material equations and torque balance equations and compared the experimental results with the theory, revealing excellent agreement.

Dynamic effects in photorefractive crystals at simultaneous read–write of holographic gratings

A two-level model of a simultaneous read–write of holographic gratings in photorefractive crystals has been developed for the nonstationary case at the applied electric field and unequality of recording beam intensities. The recurrent relationships both for the internal field amplitudes and for the amplitudes of the optical waves involved in interactions have been obtained. The use of a truncated power series expansion has allowed to obtain the expressions for diffraction efficiency and intensities of optical waves in nonstationary case. The obtained results were used for the analysis of simultaneous read–write dynamics in Bi12SiO20 crystals.

Two-level model of recording and reading of volume phase holograms in photorefractive crystals of BSO-type

A two-level model of optical transitions in crystals of BSO-type has been proposed for the effect of readout beam on the dynamic holographic grating to be taken into account, and an expression for diffraction efficiency representing the generalized formula by Vinetskii and coworkers [1–3] has been obtained.

Holographic beam coupling in anisotropic photorefractive media

The process of two-beam holographic coupling in optically anisotropic media is analyzed. We consider holographic media possessing birefringence, optical activity, and spatial modulation of these effects. Coupled equations are derived, and expressions for diffraction efficiency, angular and wavelength sensitivity, and polarization properties of the interacting beams are obtained. Results are compared with those of experiments with holograms formed in photorefractive Bi12SiO20 crystals.