Electronic and nuclear contributions to the third-order nonlinear optical properties of new polyfluroalkysulfanyl-substituted tetrathiafulvalene derivatives

From DFWM efficiency measurements, we deduce third-order susceptibility of polyfluroalkylsulfanyl-substituted TTF derivatives. To know the physical na ture of the optical non-linearities, we separate the electronic and nuclear contributions in chi ((3)). The electronic contribution of these molecules turned out dominant. We also deduce the values of the second-order hyperpo larisabilities gamma which are about 10(3) greater than the gamma value of CS2 at the same wavelength 532 nm As the absorption of the studied compound s is very weak at 532 nm, their merit factors in term of relation between t he third-order susceptibility and linear absorption coefficient are better than the ones obtained for ethylenic TTF derivatives studied previously. (C ) 2000 Elsevier Science S.A. All rights reserved.