ASSESSMENT OF 3RD-ORDER OPTICAL NONLINEARITIES IN CONJUGATED ORGANIC POLYMERS

Third-order nonlinear optical susceptibilities of substituted polythiophenes, polyanilines, and polysilanes have been estimated by third-harmonic generation measurements at 1.053 mum. Values of chi(3)(-3omega;omega,omega,omega) for new polymers-two poly(alkoxyphenylthiophenes), a fluorinated poly(alkylthiophene), and a poly(alkoxyaniline)-were found to be in the range 0.7 x 10(-12) to 2.3 x 10(-12) esu, similar to those for other substituted polythiophenes and polyanilines. Values of chi(3)(-3omega;omega,omega,omega) are correlated with the absorption maxima for series of polythiophenes, polysilanes, and polyanilines. Third-order nonlinearities are found to depend strongly on the nature of the polymer backbone and only slightly on substituents.