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 (T-NI) of a liquid crystal composed of bent-shaped molecules. The values of B and chi((3)) just above (similar to 0.3 degrees C) T-NI are similar to 8x10(-12) m/V-2 and 5x10(-20) m(2)/V-2, respectively. The estimated critical temperature T-C(*) is about 1.5 degrees C below T-NI 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.