Linear and tri-branched copolymers for two-photon absorption and two-photon fluorescent materials

The one- and two-photon properties of linear (M2) and tri-branched (M3) copolymers with triphenylamine and cyano groups in the main chain were experimentally investigated. Open-aperture z-scan experiments were performed with 1 kHz, 120 fs, and 800 nm Ti:sapphire laser pulses to measure the two-photon absorption cross sections. The two-photon cross sections of M2 and M3 were determined to be 0.304 and 1.441×10−20 cm4/Gw per repeating unit, respectively. In a CHCl3 solution, M2 and M3 emit strong frequency up-converted fluorescence under the excitation of 120 fs pulses at 800 nm with the peaks located at 561 and 542 nm.