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 x 10(-50) cm(4) s and 5 x 10(-78) cm(6) s(2), 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. (C) 2004 Elsevier B.V. All rights reserved.