Poled nematic films, where the asymmetric axis responsible for second harmonic generation (SHG) is not in the poling direction are reported. Liquid crystalline polymers containing dopant chromophores, or side chain groups with high molecular hyperpolarizabilies exhibit this effect which has potential applications in nonlinear optics.

A series of side chain liquid crystal co-polymers is prepared, starting from monomers containing both mesogenic and hyperpolarizable groups. When thin films of these polymers are poled by an electric field in the plane of the film, they exhibit optical nonlinearity both parallel and perpendicular to the direction of the poling field.

Side-chain liquid crystal polyacrylates and polysiloxanes containing different photochromic spironaphthoxazine side groups were synthesized. Thermodynamic, spectral and kinetic properties of the polymers were investigated. The structure of the mesophase is discussed.

Nematic films doped with molecules of high nonlinear polarizability can exhibit two-dimensional asymmetry after electric-field poling along one direction only. Consequently, these films exhibit more nonzero components of the second-order susceptibility tensor than are obtained through usual poling techniques. These films can exhibit very high nonlinear optical coefficients (close to 10−7 esu/cm3) and retain most of their nonlinearity one week after removal of the poling field.