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 (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 (~0.30.2em0ex^∘C) TNI are ~8×10^-120.3em0exm∕V² and 5×10^-200.3em0exm²∕V², respectively. The estimated critical temperature TC* is about 1.50.2em0ex^∘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.