Multiphoton absorption of solutions of polydiacetylene polyDCHD-HS measured using ps< i> Z-scan at 1064 and 1500 nm

The nonlinear absorption of benzene and toluene solutions of polydiacetylene polyDCHD-HS was measured at k ¼ 1064 and 1500 nm by using Z-scan and picosecond pulses with a trimmed Airy beam configuration. In the data analysis, we took into account both the saturation of the open aperture Z-scan traces occurring for high values of nonlinear absorption and the possible occurrence of cross-talk effects between nonlinear refraction and multiphoton absorption. The polymer exhibits three-photon absorption at both 1064 and 1500 nm. The molecular three-photon absorption coefficient at 1064 nm was r3 ¼ 1:8 1038 cm6=W2 and r3 ¼ 2:3 1038 cm6=W2 in toluene and benzene, respectively, while at 1500 nm it was r3 ¼ 1:5 1039 cm6=W2 in toluene. On this basis, the optical limiting behavior of polyDCHD-HS in the near infrared range is also shown.