RE-CHI((3)), RE-CHI((5)), AND RE-CHI((7)) MEASURED IN POLY(PHENYLENE ETHYNYL SILANE)S BY THE Z SCAN TECHNIQUE

Optical nonlinear susceptibilities were measured in Poly(phenylene eth ynyl silane) (PPES1) and Poly(phenylene ethynyl disilane) (PPES2) at 5 90nm and 1064nm. Both the real and imaginary parts of chi((3)) were ev aluated with the Z scan technique using closed and open apertures, res pectively. Closed aperture scans of PPES1 exhibited the classic negati ve Re chi((3)) peak valley signature, whereas, closed aperture scans o f PPES2 displayed interesting additional features. These features are present at both 590nm and 1064nm, and indicate the presence of alterna ting sign higher order nonlinearities with negative chi((3)), positive chi((5)), and negative chi((7)).