Measurement of two-photon absorption coefficient of dye molecules doped in polymer thin films based on ultrafast laser ablation

Two-photon absorption cross-section of a series of dyes (1a–3a) in polymer thin films was determined by measuring the femtosecond laser ablation threshold. The ablation threshold decreased gradually when the dopant increased. The two-photon absorption cross-section of the dye molecules dispersed in the polymer film was estimated by using the theoretical relationship between the ablation threshold of the blended polymeric thin films and the dye concentration. The relative values of two-photon absorption cross-section are in good agreement with those measured in solution. On the other hand, the absolute values are smaller than the latter.