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

We report the determination of the Kerr constant (B) and the real part of the third-order nonlinear optic susceptibility (chi(3)) above the nematic-isotropic phase transition temperature (TNI) of a liquid crystal composed of bent-shaped molecules. The values of B and chi(3) just above (approximately 0.3 degrees C) TNI are approximately 8x10(-12) m/V2 and 5x10(-20) m2/V2, respectively. The estimated critical temperature TC* is about 1.5 degrees 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.