Degenerate-wave mixing in new dithienylethylenes

We report the measurement of the degenerate fourth-wave mixing (DFWM) of ne w dithienylethylenes in chloroform solutions at lambda = 532 nm in ps regim e with different numbers of pi-conjugated bonds. From these measurements, w e evaluated the values of the second order hyperpolarizabilities gamma, whi ch are about 10(3) larger than the gamma value of CS2. The influence of pi- conjugated bonds on the third-order susceptibilities and appropriate figure s of merits is discussed. The more important seems to be the possibility of a simultaneous increase of the third-order susceptibilities, together with the decrease of the absorption coefficients that open a possibility of the ir use as promising materials for laser wavelengths mixing. (C) 2000 Elsevi er Science S.A. All rights reserved.