Chiral Nonlinear optics in oxides, polymers and liquid crystals

Abstract

The linear electro-optic (EO) effect, a second order nonlinear optical process, has been studied in optically active material systems including Bi12SiO20 oxide (BSO oxide), side-chain poly-isocyanate polymer with Disperse-Bed 1 doped, and bent-core chiral liquid crystals. In an isotropic BSO sample, the breaking of intrinsic centrosymmetry allowed the EO modulation of the refractive index under an external modulation field. The superposition principle of optical activity and optical birefringence for the total phase shift was extended to the determination of the EO coefficient in the BSO crystal. In the case of polymer and liquid crystal samples, electro-gyration (EG) effects were observed. Upon application of a Corona field to a chiral birefringent polymeric slab waveguide film, changes in the polarization rotation were observed due to nonlinear changes in the optical activity, as well as the birefringence. Moreover, in a mixture of bent-shaped molecules having both optical activity and birefringence, we investigated the strong intensity modulation related to the nonlinear optical responses of both the optical rotatory power and the birefringence. These results open the possibility of chiral EO modulation in nonlinear optically active material systems.