Analytical model of PDLC holographic polarization gratings formation under the influence of light-induced absorption changing
Tomsk State University of Control System and Radioelectronics, Russia
In this paper we develop an analytical model of the holographic polarization gratings (HPGs) formation in polymer-dispersed liquid crystals (PDLCs). The light-induced absorption coefficient changing is taken into account. Holographic formation by two orthogonally polarized beams is con-sidered. HPGs formation in PDLCs is possible due to the light-induced periodic spatial inhomogeneity of the optical anisotropy of the material caused by the superposition of two plane coherent orthogonally polarized waves on the sample plane, and stabilized as a result of phase separation of PDLC components during photopolymerization process. In this case, the phase difference between the interfering waves only leads to a polarization state changing of the resulting field, intensity modulation is absent. Because NLC is able to orient in the direction of the electric field vector of the light field under the influence of the photo-induced Fredericks effect, then gratings with periodically repeated NLC molecules orientations in polymer droplets are formed in PDLC after exposure. The resulting mathematical model describes the holographic formation of polarization gratings in PDLC under the influence of the light-induced absorption. Obtained results can be used to develop a model of light beams diffraction on the spatially inhomogeneous HPGs.