PRELIMINARY OPTICAL STUDY ON ER FLUIDS

Linear and nonlinear optical study on electrorheological (ER) fluids i s reported. The ER fluids under the investigation were glass beads, ze olite and ferroelectrics. The linear optical response of some ER fluid s showed sharp changes near critical electric fields. An enhancement o f electric field induced second harmonic generations (EFISH) was obser ved as the function of E(2), where E is the external electric field. T he said enhancement is considered to be corresponding to a modulation of the material's refractive index associated with the electric held i nduced polarization of the delocalized electrons. The enhanced nonline ar optical response on the transition between liquid and solid states can be related to the phase transition in ER fluids.