χ(3) measurements in novel poly(2′,5′-dioctyloxy-4,4′,4″-terphenylenevinylene) using the Z-scan technique

Abstract

We investigated the third-order nonlinear optical (NLO) properties of three poly(2′,5′-dioctyloxy-4,4′,4″-terphenylenevinylene)s having different cis/ trans-vinylene ratios. The nonlinear measurements were performed at λ=532 nm in chloroform solutions using single-beam Z-scan technique with picosecond laser pulses. All the investigated polymers exhibit a moderate two-photon resonance at this wavelength. On the contrary, the magnitude of the nonlinear refractive index is high and shows a considerable dependence on the cis/ trans ratio of the double bonds. The largest third-order nonlinear optical susceptibility, | χ (3)|=(5±1)×10 −10 esu, was measured for a polymer with all monomers having vinylene unit in trans-configuration.