Highly polar chromophores in poled polymer films characterised by second harmonic generation

Evidence for exceptionally high dipole moments in a series of nonlinear optical chromophores doped into poly(methyl methacrylate) films has been found. The strength of the poling field/dipole interaction is measured directly from incidence angle dependence of the second harmonic (SH) intensity generated from corona poled films. Values of the dipolar orientation parameter, <cos θ>, greater than 0.5 can be achieved for externally applied fields of only MV m−1. Quantum chemical calculations of the evolution of the dipole moments of the compounds versus local reaction field support the conclusion that extremely high dipole moments characterise these molecules.