Third-order nonlinear optical properties of copoly(2,3,5,6-tetrafluoro-1,4-phenylenevinylene-2,5-dialkoxy-1,4-phenylenevinylene)s, a novel class of push-pull substituted PPVs

A series of copoly(2,3,5,6-tetrafluoro-1,4-phenylenevinylene-2,5-dioctyloxy-1,4-phenylenevinylene)s containing variable ratios of tetrafluorophenylenevinylene and dialkoxyphenylenevinylene repeating units has been synthesized via the Stille cross-coupling reaction in order to investigate the influence on the chi((3)) of the simultaneous presence of electron-deficient and electron-rich aromatic monomers in the PPV backbone. Third-order nonlinear optical properties of the resulting materials have been studied in chloroform solutions at lambda=1064 nm using the picosecond Z-scan technique. The nonlinear refractive index has been found to be negative, strongly dependent on the copolymer composition, and as high as (-10+/-2)x10(-12) cm(2)/W.