Thienylene polyazomethines and polyazines as third-order nonlinear optical materials

Linear and third-order nonlinear optical (NLO) phenomena have been studied in three thiophene-containing polyimine classes. A complete characterization has been performed determining the real part of the refractive index n, its imaginary part k, and the third-order NLO value. The NLO values derived for the polymers are related to both the electronic property and backbone conformational arrangement, affecting the overall conjugation. The highest third-order NLO coefficient has been measured on a very homogeneous spin-coated film of dialkyl substituted polyazine, showing a value of 5.2x10^11 esu at 1710 nm, where the material is essentially transparent.