One-, two-, and three-photon absorption Induced fluorescence of a novel chromophore in chloroform solution

The one-, two-, and three-photon absorption induced fluorescence spectrum of a novel chromophore was investigated using an optical parametric amplifier (OPA) pumped by a Ti:sapphire laser. The shorter wavelength laser radiation emitting from 600 to 1000 nm was converted from 1200 to 2000 nm laser pulses by second harmonic generation using a nonlinear optical crystal BBO, (β-barium borate). Four resonance peaks were found in the fluorescence spectrum when the excitation wavelength was tuned from 600 to 2000 nm. A three-level model was constructed to derive an equation to account for the incident excitation laser dependence of the fluorescence intensity.