Structural and upconversion fluorescence properties of Er 3+/Yb 3+-codoped oxychloride lead–germanium–bismuth glass

Abstract

Structural and infrared-to-visible upconversion fluorescence properties of Er 3+/Yb 3+-codoped oxychloride lead–germanium–bismuth glass have been studied. The Raman spectrum investigation indicates that PbCl 2 plays an important role in the formation of glass network, and has an important influence on the upconversion luminescence owing to lower phonon energy. Intense green and red emissions centered at 525, 546, and 657 nm, corresponding to the transitions 2H 11/2→ 4I 15/2, 4S 3/2→ 4I 15/2, and 4F 9/2→ 4I 15/2, respectively, were observed at room temperature. The quadratic dependence of the 525, 546, and 657 nm emissions on excitation power indicates that a two-photon absorption process occurs under 975 nm excitation.