2ND-ORDER NONLINEAR OPTICAL EFFECTS IN NOVEL SIDE-CHAIN LIQUID-CRYSTALLINE POLYMERS AND MONOMERS UNDER BIAS OF AN APPLIED DC ELECTRIC-FIELD

Second-order nonlinear optical susceptibilities of a series of newly synthesized liquid crystalline polymers and corresponding monomers were measured by using second-harmonic generation. A substituted stilbene moiety was selected as the main conjugated pi-electronic structure, and systematic modifications were made at the site of the donor and in the conjugation path to compare the roles of various donors and charge-transferring linkages in the second-harmonic-generation process. The beta values extracted from the measurements made on solutions and on thin films yielded similar values for the monomers and the corresponding polymers. The variations in beta values are discussed in terms of molecular structural properties, charge-transferring power of the donors, and dispersion effect.