No abstract

The large electronic second order nonlinear optical susceptibilities of organic molecules can be built into bulk systems by imparting polar orientational order to an ensemble of nonlinear optical dopants. The noncentrosymmetric orientational order required for second order nonlinear optical processes in noncrystalline materials, such as molecule-doped liquid crystals and polymer glasses, has been demonstrated using electric field poling.[1] [2] [3] [4] The relationship between the second order molecular tensor susceptibility and the bulk tensor susceptibility of a polymer doped with optically nonlinear molecules has been recently calculated in the mean field approximation for poled materials under the influence of other bulk ordering forces [5] such as uniaxial stress. [6] Also, it has been previously shown that optical second harmonic generation can be a sensitive probe of molecular order.[7] In this paper, the tensor properties of the second order susceptibility of films poled under uniaxial stress in the direction of the poling field are determined. It is shown that both the magnitude and tensor properties of the second order susceptibility can be continuously varied with poling field and stress.