Dual-frequency coherent induction of non-centrosymmetry in a chiral bisazo-dye doped polymer film

All-optical poling technique permits the optical orientation of dye molecules in a polymer film. Non-centrosymmetry in azo-dye doped polymer systems is induced by a dual-frequency coherent excitation. We demonstrate that a polymer thin film doped with an almost centrosymmetric bisazo-molecule exhibits second harmonic generation after all-optical poling. The effective nonlinear optical coefficient χeff(2) was estimated as 3.9 pm/V.