Abstract

We have measured the optically induced birefringence of several anisotropic Kerr materials. An artificial Kerr material is a suspension of dielectric particles whose size is smaller than the wavelength of light. It has been predicted that artificial Kerr materials that are anisotropic should have large optical nonlinear susceptibilities resulting from the reorientation of the particles when a strong optical field is applied.¹ The materials we have studied include TiO₂, polytetrafluoroethylene (PTFE), and poly-γ-ben zyl-L-glutamate (PBLG). The optical anisotropy of these materials can result from form birefringence due to the anisotropic shape of the particle or from intrinsic birefringence of the material because of its crystalline structure. We have studied several different particle shapes including nearly spherical and needlelike geometries. The induced birefringence is measured using an argon-ion laser for the various materials at several different concentrations. The nonlinear susceptibility χ⁽³⁾ is calculated from the measured induced birefringence. We find that is as large as 10^-5 esu. The measured response time for TiO₂ suspended in water is ~1 ms which is ~100 times faster than the response time of isotropic Kerr materials where the nonlinearity results from the translational motion of the particles.

© 1991 Optical Society of America