Two-photon pumped upconversion and nonlinear optical properties of a new lasing dye: HMASPS

Two-photon pumped frequency upconversion optical properties and two-photon absorption (TPA) induced nonlinear absorption of a new dye, trans-4-[p- (N- hydroxyethyl-N-methylamino)styryl]-N-methylpyridinium p-toluene sulfonate ( abbreviated to HMASPS) have been experimentally investigated. This new dye exhibits strong superradiation properties when the pumping power is above i ts threshold. The superradiation upconversion efficiency from 900 to 1150nm and the nonlinear absorption from 720 to 1100nm have been measured. The la rgest effective molecular TPA cross-section was measured to be 44.3x10(-48) cm(4).S.photon(-1) at 920nm. At 1064nm, it was 2.77x10(-48) cm(4).s.photon (-1), much smaller than that at 920nm. The highest conversion efficiency is 7% at 990nm, whereas 4.2% at 1064 nm.