CHIRALITY IN SURFACE NONLINEAR OPTICS

The efficiency of second-harmonic generation from chiral surfaces and thin films ii; different for left- and right-hand circularly-polarized fundamental light. Such optical activity can occur in the electric-di pole approximation. However, to explain our results for chiral polymer films, magnetic contributions to the nonlinearity must be included. A technique that uses a quarterwave plate to continuously vary the pola rization of the fundamental beam was used to determine the relative co mplex values of the components of the tensors that characterize the no nlinear interaction. The largest magnetic components were similar to 2 0% of the largest electric components. Second-harmonic generation from achiral anisotropic surfaces tan also lead to optical activity. This occurs if the orientation of the anisotropic sample mal;es an otherwis e achiral experimental arrangement chiral, The effect occurs in the el ectric-dipole approximation and changes sign as the handedness of the setup is reversed, (C) 1998 Elsevier Science B.V.