Abstract

Thiophene-based polymers have recently been shown to have large third-order nonlinear susceptibilities, making them excellent candidates for use in nonlinear optical devices We have produced what we believe to be the first high quality thin films of alkoxy-substituted polythiophenses by the Langmuir-Blodgett technique. This method allows the fabrication of films with regular packing of molecules and well-defined thickness. Conditions for successful deposition of polymers were identified by pressure/ area isotherms and regular stacking of layers is demonstrated by UV–visible absorption spectra of films. Third-harmonic generation measurements of films with 4–30 layers of polymer deposited on glass substrates were carried out using selected 60-ps pulses from a mode-locked Q-switched Nd:YLF laser operating at 1053 nm. ⁽³⁾ values for polythiophenses are comparable to those of other conjugated organic polymers, in the range of 10^-12 to 10^-11 esu.

© 1991 Optical Society of America