Enhancement of the 1.31-mu m emission properties of Dy3+-doped Ge-Ga-S glasses with the addition of alkali halides

Alkali halides such as KBr, KI, CsBr, and CsI were added to Dy3+-doped Ge-G a-S glasses, and their effects on the 1.31-mum emission property were inves tigated, The intensities of the 1.31-mum emission (F-6(11/2) . H-6(9/2) --> H-6(15/2)) increased at the expense of the 1.75-mum emission intensity (H- 6(11/2) --> H-6(15/2)) With the alkali halide addition. The lifetimes of th e 1.31-mum emission level also increased as much as 35 times from 38 mus fo r Ge-Ga-S glass to 1320 mus for the glass containing 10 mol% CsBr. These en hancements occurred only when the ratio of MX (M = K, Cs; X = Pr, I)/Ga was equal to or larger than unity, Raman spectra of Ge-Ga-S-CsBr glasses indic ated the formation of [GaS3/2Br](-) complexes, which provide the preferred sites for Dy3+. Due to this new local environment of Dy3+, the multiphonon relaxation rates from the Dy3+:F-6(11/2) . H-6(9/2) level decreased by appr oximately four orders of magnitude. The enhancement in the 1.31-mum emissio n properties with alkali halide addition supports the potentials of these g lasses as hosts for the Dy3+-doped fiber-optic amplifiers.