Tm3+ are new candidates for optical amplifiers in the 1.5micrometers region, the S band. For the moment, Tm3+-doped Fibers Amplifiers (TDFA) h ave been studied in fluoride matrices because of the lowest phonon energy of this glasses compared to the silica ones. We proposed to evaluate the spectroscopic potential of this ion in sulfide GeGaSSb glasses where the phonon energy is around 350cm-1. Absorption and emission cross sections were measured. Lifetime measurements were carried out. Results were compared with the Judd-Ofelt calculations.© (2002) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.