Broad band excitation of Dy3+ emission by localized tail state absorption in chalcogenide glasses

We have previously reported investigations of Er-doped and Pr-doped Ge₃₃As₁₂Se₅₅ glasses, both of which displayed exceptionally broad rare earth photoluminescence (PL) bands. In addition, the photoluminescence excitation (PLE) spectra of both the 1640 nm Pr(3+) emission (³F_→³ H₄) and the 1540 nm Er³⁺ emission (⁴ I_13/2→⁴I_15/2) exhibit nearly identical broad excitation bands from ~500-1000 nm. On the basis of their line shapes, these broad PLE bands were attributed to absorption by defect- or impurity-related localized band tail states in the host glass, which then transferred their energy to the rare earth atoms. We present here a parallel investigation of Dy-doped Ge₃₃As₁₂Se₅₅ glass. This is an excellent system in which to test our hypothesis concerning the origin of the broad PLE bands because the Dy atoms have a series of emissions ranging from 2800 nm to 1150 nm, all terminating in the ground slate. In addition, Dy-doped chalcogenide glasses are of technological interest because of possible application in fiber amplifiers