Measurement system for optical Kerr effect induced by continuous wave laser

An experimental technique was developed for studying the optical Kerr effect induced by a cw Ari laser with 500 mW output. A Pockels cell was used for modulating the pump laser so that the polarization changed periodically between the vertical and horizontal plane. The dielectric anisotropy thus induced in a sample liquid was probed in the ellipsometry with a He-Ne laser. The system was applied to nitrobenzene and p-n-hexyl p'-cyanobiphenyl (6CB), a nematogen in the isotropic phase. The observed birefringence showed a linear dependence on the pump laser intensity and the gradient yielded the Kerr constant: B = 5.75 x 10(-14) V-2 m at 30 degrees C in nitrobenzene and B = 6.72 x 10(-12)(T - T*)(-1) V-2 m in 6CB, T* being the virtual transition temperature to the nematic phase. This technique can be used for :investigating the relaxation of molecular orientation in frequency domain. (C) 1998 American Institute of Physics.