High third-order nonlinear optical susceptibility in new fluorinated poly(p-phenylenevinylene) copolymers measured with the Z-scan technique

The third-order nonlinear optical properties of a series of copoly(2,3,5,6-tetrafluoro-1,4-phenylenevinylene-2,5-dioetyloxy-1,4-phenylenevinylene) that contain variable ratios of two differently substituted monomers have been studied in chloroform solutions at lambda = 1064 nm by the picosecond Z-scan technique. Nonlinear refractive index n(2) of the samples investigated has been found to be negative, and a strong dependence of its magnitude on the copolymer's composition has been observed. The highest third-order nonlinear optical susceptibility, \chi((3))\ = (6 +/- 2) X 10(-10) esu, was measured for a copolymer obtained by reaction of equimolar quantitites of the parent monomers. (C) 2002 Optical Society of America.