Two-photon absorption and frequency-upconversion properties of a new organic dye HMASPS

Two-photon absorption (TPA) and frequencyupconversion properties of a new upconversion laser dyetrans-4-p-(N-hydroxyethyl-N-methyl-amino)styryl]-N-methylpyridinium toluene-p-sulfonate (abbreviated to HMASPS) were reported in this note. The linear absorption, TPA, single-photon induced fluorescence, TPA induced fluorescence and TPA induced upconverted lasing spectra of HMASPS solution in dimethyl formamide (abbreviated to DMF) were measured at room temperature. The red shift for the central wavelength of TPA induced fluorescence peak, which was compared with that of the single-photon induced fluorescence peak, and the blue shift for that of TPA induced upconverted lasing compared with that of TPA induced fluorescence, were explained by using re-absorption effect. TPA peak was at 930 nm. There is an 11 nm blue shift for two-photon energy of TPA peak compared with the linear absorption peak. The molecular TPA cross-section σ₂ ^9′ at 1064 nm was measured to be 6.0×10⁻⁴⁸ cm⁴ · s/photon by using the open aperture Z-scanning system. The highest upconversion efficiency was measured to be 8.4% at 1064 nm.