Abstract

Third-harmonic generation is used to measure the third-order susceptibility of side- chain-substituted polymers. Both the magnitude and phase ofχ⁽³⁾(3ω) are measured for a family of donor-acceptor diphenyl polyene side-chain-substituted polymers. Dimethylaminonitrostilbene (DANS) and methyloxynitrostilbene (MONS) side-chain- substituted polymer thin films are modelled by an inhomogeneously broadened two-level system. In addition to their very good linear and electro-optical properties, this class of organic polymers show χ⁽³⁾values comparable to those of fully conjugated backbone polymers. The values of the magnitude and phase of χ(3ω) have been measured at 953, 1064, 1573, and 1904 nm. The dispersion of χ⁽³⁾(3ω) for DANS and MONS side chain polymers agrees with the predictions of the two-level model. The values of the phase of χ⁽³⁾(3ω) are explained by dominant charge transfer mesomeric moments in the expression of χ⁽³⁾(3ω). The mesomeric moments obtained from our χ⁽³⁾ measurements are in excellent agreement with those found in the literature.

© 1990 Optical Society of America