Visible and near infra-red up-conversion in Tm3 /Yb3 co-doped silica fibers under 980 nm excitation

Abstract

The spectroscopic properties of Tm3+/Yb3+ co-doped silica fibers under excitation at 980 nm are reported. Three distinct up-conversion fluorescence bands were observed in the visible to near infra-red regions. The blue and red fluorescence bands at 475 and 650 nm, respectively, were found to originate from the 1G4 level of Tm 3+. A three step up-conversion process was established as the populating mechanism for these fluorescence bands. The fluorescence band at 800 nm was found to originate from two possible transitions in Tm3+; one being the transition from the 3H4 to 3H 6 manifold which was found to dominate at low pump powers; the other being the transition from the 1G4 to 3H 6 level whic..