Design of optimized photorefractive polymers: a novel class of chromophores

A fully tensorial formulation is presented of the photorefractive (PR) Kerr effect, providing a convenient formalism for the calculation of diffraction efficiencies for various geometries. A detailed microscopic interpretation of the PR Kerr effect is also presented in terms of the relevant molecular linear and nonlinear optical properties. This approach allows the identification of the dominant molecular contributions and a better establishment of design criteria for the optimization of functional dyes for organic PR materials. These generalized principles are illustrated with a prototype chromophore, 2,6-di-n-propyl-4H-pyran-4-ylidenemalonitrile (DPDCP). The linear and nonlinear optical properties of this compound are obtained from a complete set of refractive index, permittivity, depolarized Rayleigh scattering, electric field-induced second harmonic generation (EFISH), and UV-VIS spectroscopic measurements, and quantum chemical calculations.