ELECTRIC POLING ENHANCEMENT OF OPTICAL NONLINEARITY IN LANGMUIR-BLODGETT FILMS

摘要

The rotation-angle second harmonic generation (SHG) technique was used to investigate change of molecular orientation in Y-type interleaving hemicyanine/arachidic acid LB multilayer samples poled by a DC electric field in the substrate normal. The external field aligned the hemicyanine chromophore axes along the poling field direction. With increasing the poling voltage, the degree of the dipping-induced in-plane anisotropy was reduced monotonically, while the SHG intensity from the poled samples increased quadratically due to molecular reorientation towards the substrate normal, and reached an increment by an order of magnitude with a field of 10~6 V/m and poling time 10 min at room temperature.