Abstract

Intensity of the 2.9μm fluorescence from Dy³⁺ in Ge₂₅Ga₅S₇₀ glass increased with increasing Tm³⁺ content when the Dy³⁺ concentration remained constant, which indicates the presence of an efficient energy transfer between Tm³⁺ and Dy³⁺. Analyses of the emission intensities and decay times suggested that a direct energy transfer from the Tm³⁺:³F₄ level to Dy³⁺:⁶H₁₁/₂ level occurred after a fast diffusion-limited migration of the excitation energy among Tm³⁺. A decrease in the measured lifetimes of the Tm³⁺:³F₄ level and a wide spectral overlap between the Tm³⁺: 1.8μm emission and the absorption of Dy³⁺: ⁶H_15/2➝ ⁶F_11/2 also supported the proposed energy transfer scheme. Multiphonon relaxation rates in sulfide glasses were orders of magnitude lower than those for conventional oxide glasses.

© 1997 Optical Society of America