Tunable "optical activity" in electrorheological fluids

The "optical activity" of adjustable periodic structure material (SiO2 and pentaerythrital electrorheological (ER) fluids) is firstly investigated using two kinds of setup. It is found that the rotation angles can be tuned by the external electric field and weight concentrations, and the sign of the rotation angle is negative, so, the used ER fluids are defined as the left-handed optically active substances under the application of electric field. The laser diffraction patterns are also observed in the ER fluids, which indicates the formation of alignment. It is thought that the symmetry breaking of structure induced by applied electric field is the origin of the "optical activity" in the ER fluids. The electrically tunable "optical activity" will find innovative applications in displays, optical devices and other fields. (C) 2004 Elsevier B.V. All rights reserved.