CHIRAL MATERIALS IN SECOND-ORDER NONLINEAR OPTICS

Abstract

We review how chirality can lead to new types of second-order nonlinear optical materials. Chiral molecules are noncentrosymmetric with a nonvanishing electric-dipole-allowed second-order response, which persists in macroscopic samples with high rotational symmetry such as isotropic solutions. On the other hand, contributions of magnetic-dipole interactions, which can be strong in chiral materials, allow second-order processes in centrosymmetric materials. The magnetic contributions of thin films of chiral polyisocyanides and polythiophenes are comparable to electric contributions. Components of the electric-dipole susceptibility tensor associated with chirality dominate the response of thin films of a chiral helicenebisquinone.