Kerr constant and third-order nonlinear optic susceptibility measurements in a liquid crystal composed of bent-shaped molecules

Abstract

We report the determination of the Kerr constant (B) and the real part of the third-order nonlinear optic susceptibility (χ(3)) above the nematic-isotropic phase transition temperature (TNI) of a liquid crystal composed of bent-shaped molecules. The values of B and χ(3) just above (∼0.3 °C) TNI are ∼8× 10-12 m V2 and 5× 10-20 m2 V2, respectively. The estimated critical temperature TC* is about 1.5 °C below TNI indicating that the nematic-isotropic (NI) transition is weakly first order as in the case of calamitic liquid crystals. The temperature-dependent Kerr constant is found to be in good agreement with the predictions of the Landau-de Gennes theory. The experimental results are compared with those in a calamitic liquid crystal material with negative dielectric anisotropy in the nematic phase. © 2008 The American Physical Society.