1.3-mu m-emission properties and local structure of Dy3+ in chalcohalide glasses

Abstract

Spectroscopic properties and local structure of rare-earth ions in Ge-Ga-S glasses with the addition of alkali halides were investigated. The intensity of the 1.31-mum emission from Dy3+ (F-6(11/2) H-6(9/2) --> H-6(15/2)) increased sharply when the appropriate. amount of alkali halides was added, at the expense of the 1.75-mum emission intensity (H-6(11/2) -->H-6(15/2)). The lifetimes of the 1.31-mum emission level also increased as much as 35 times from 38 mus for Ge-Ga-S glass (0.1 at.% Dy3+) to 1320 mus for glass containing 10 mol% of CsBr. These enhancements occurred only when the ratio of MX(M = K,Cs and X = Br, I)/Ga was equal to or larger than unity. Phonon side band (PSB) showed that the several local phonon modes, with the frequencies around 100 cm(-1), were coupled to 4f electrons of Eu3+. The nearest neighbors of Eu3+ ions are composed of halogen ions that are part of well-structured complex such as EuCl3, tetrahedral [GaS3/2Cl](-) subunit and/or Ga2Cl6. A small amount of As was added to increase the resistivity against the recrystallization during re-heating. The best composition for practical usage was 0.7 [Ge0.25As0.10S0.65]-0.15 GaS3/2-0.15 CsBr. This glass also exhibited high resistance against the attack of liquid water and is therefore a potential material for efficient fiber-optic amplifiers.