Two-photon-pumped cavity lasing in a dye-solution-filled hollow-fiber system

Abstract

Two-photon-pumped cavity lasing has been achieved in a dye-solution-filledhollow-fiber configuration that provides both a longer gain lengthand a higher local pump intensity. The gain medium is a solutionof the new dye 4-[N-(2-hydroxyethyl)-N-(methyl)amino phenyl]-4(')-(6-hydroxyhexylsulfonyl)stilbene in dimethyl sulfoxide, which shows a strong two-photon-absorption-inducedfluorescence when excited with near-infrared radiation. When thesystem is pumped with 800-nm 5-ns laser pulses, frequency-upconvertedcavity lasing can be observed with a peak lasing wavelength near565 nm and a 2-3.5-ns pulse duration. One of the major advantagesof using a hollow-fiber geometry is the low two-photon pump threshold,which was measured to be as low as 20-30 mu J for a 15-cm-long hollow-fibersample of 100-mu m internal diameter. The conversion efficiency fromthe absorbed pump energy to the upconverted lasing output was 2.3%.(C) 1995 Optical Society of America