Upconversion and Nonlinear Absorption Properties of Two-photon Absorption Dye: HMASPS

Two photon pumped frequency upconversion and the two-photon absorption (TPA) induced nonlinear absorption of a dye, trans-4-[p-(N-hydroxyethyl-N-methylamino)styryl]-N-methylpyridinium p-toluene sulfonate (abbreviated as HMASPS) have been experimentally investigated. The dye exhibits strong superradiation properties when the pumping power is above its threshold. Furthermore, the lasing upconversion efficiencies from 900 to 1150 nm and the nonlinear absorption from 720 nm to 1100 nm have been measured. The largest effective molecular TPA cross section was measured to be 44.3×10 -48 cm 4s/photon at 920 nm. At 1064nm, it was 2.77×10 -48 cm 4s/photon. The highest upconversion efficiency is 7% at 990 nm, whereas 4.3% at 1064 nm.