12 September 2003 Time history of laser pulse polarization transformation as a tool of the isotropic-nematic phase transition in liquid crystals
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Abstract
We theoretically investigate in the aberrationless approximation the self-action of the elliptically polarized Gaussian pulse during its propagation in a thin dish with a nematic liquid crystal in the isotropic phase. Quadrature formulas are obtained to describe the time history of the intensity, the elliptisity degree and the rotation angle of the polarization ellipse of the output radiation at the different points of the beam cross-section. They are expressed in terms of the parameters describing two, essential near the temperature of the isotropic-nematic phase transition, mechanisms of the spatial nonlocality of the nonlinear medium optical response, and in terms of the other parameters, which describe the nematic liquid crystal and the elliptically polarized incident pulse. The former mechanism is specified by the medium heating due to light absorption; the latter is determined by the fluctuations of the nematic liquid crystal order parameter tensor near the temperature of the isotropic-nematic phase transition. It is shown that for some values of temperature and of the nematic liquid crystal parameters the elliptical polarization of the incident pulse, which is constant at the entry of the thin dish, transforms into the linear or another different elliptical one at the exit and keeps this new state up to the pulse tail. The dependence of the ellipticity degree on time becomes significantly nonmonotonic and changes its sign in some cases. The nonlocality of the nonlinear medium optical response weakens these transformations.
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Vladimir A. Makarov, Vladimir A. Makarov, Tamara M. Il'inova, Tamara M. Il'inova, Tatiana B. Marchenko, Tatiana B. Marchenko, Aleksandr P. Shkurinov, Aleksandr P. Shkurinov, Alexander S. Zolot'ko, Alexander S. Zolot'ko, } "Time history of laser pulse polarization transformation as a tool of the isotropic-nematic phase transition in liquid crystals", Proc. SPIE 4972, Nonlinear Frequency Generation and Conversion: Materials, Devices, and Applications II, (12 September 2003); doi: 10.1117/12.479004; https://doi.org/10.1117/12.479004
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