The Cubic Susceptibility Dispersion Of Poly(4-Bcmu) Thin-Films - 3Rd Harmonic-Generation And 2-Photon-Absorption Measurements

The near infrared dispersion of the third order nonlinear optical susceptibility, chi(3), of poly[5,7-dodecadiyn-1,12-diol-bis(n-butoxycarbonyl-methyl-urethane)], poly(4-BCMU), is investigated by third-harmonic-generation and two-photon-absorption. A four level model gives a good fit to the measured dispersions in the range of 0.770-mu-m to 1.904-mu-m. The coupling between the first 1B(u) state and two 1A(g) states, located above and below it, control the dispersion of chi-(3), in the linear transparency region of poly(4-BCMU)