Multiphoton Absorption Studies in Porphycenes Using Picosecond and Femtosecond Pulses

We present our results obtained from the Z-scan measurements in porphycenes performed using similar to 2 picosecond (ps) and similar to 40 femtosecond (fs), 800 nm pulses with a repetition rate of 1 kHz delivered by amplified Ti:sapphire laser systems. Open aperture Z-scan data demonstrated interesting multi-photon absorption properties for these molecules. In the ps regime these compounds exhibited two-photon absorption (2PA) at lower peak intensities whereas three-photon absorption (3PA) was dominant mechanism observed at higher peak intensities. In the fs regime saturable absorption was the mechanism detected. Closed aperture data was collected to evaluate the nonlinear refractive indices of these molecules in both the time domains. The magnitude of n(2) was similar to 10(-17) cm(2)/W in the fs regime and similar to 10(-15) cm(2)/W in the ps regime.