Three-photon absorption of copper phthalocyanine solution by femtosecond Z-scan technique

The nonlinear absorption (NLA) properties of copper phthalocyanine (CuPc) solution in acetone were investigated by the femtosecond open-aperture (OA) Z-scan technique. The reverse saturable absorption (RSA) phenomenon was observed. And the physical mechanism of RSA effect was revealed, which was originated from three-photon absorption. Moreover, the influences of concentration and excitation laser power on the NLA of CuPc solution were studied respectively. Results showed that the RSA effect increased with the increase of sample concentration and excitation laser power. It indicated that the CuPc could be a promising candidate for optical limiting material.