Two- and three-photon excited fluorescence in Y-shaped molecules

In this work, we have studied the two- and three-photon excited fluorescence on a new series of Y-shaped chromophores, using pulses at 750 and 1400 nm from an optical parametric amplifier pumped by 150 fs pulses from a Ti:sapphire chirped pulse amplified system. The measured two- and three-photon absorption cross-sections are in the order of 1000 × 10−50 cm4 s and 5 × 10−78 cm6 s2, respectively. Besides, the two-photon excited fluorescence signal, achieved using low energy pulses (Ti:sapphire modelocked oscillator), were used in an evolutionary strategy to optimize either the laser pulse or the two-photon excited fluorescence.