Green up-conversion in Yb³⁺-Tb³⁺ and Yb³⁺-Tm³⁺-Tb³⁺ doped fluoro-germanate bulk glass and fibre

Scarnera, V., Richards, B., Jha, A., Jose, G. and Stacey, C. (2010) Green up-conversion in Yb³⁺-Tb³⁺ and Yb³⁺-Tm³⁺-Tb³⁺ doped fluoro-germanate bulk glass and fibre. Optical Materials, 33 (2), 159-163. (doi:10.1016/j.optmat.2010.08.006).

Abstract

Yb³⁺–Tb³⁺ and Yb³⁺–Tm³⁺–Tb³⁺ doped fluoro-germanate glass samples were fabricated in bulk and fibre form. Bright up-conversion has been obtained by exciting the samples with a 975 nm laser source, and the power dependence of the up-conversion intensities with respect to the excitation power has been characterised. Two mechanisms must be taken into account to explain the population of the ⁵D₄ level of the terbium ions in these experiments; namely multi excited state absorption (MESA) and cooperative up-conversion (CU). While in the Yb³⁺–Tm³⁺–Tb³⁺ samples both MESA and CU contribute simultaneously to the ⁵D₄:Tb³⁺ population, in the Yb³⁺–Tb³⁺ case a pure CU mechanism is responsible for the ⁵D₄:Tb³⁺ population. In the fibre geometry, the re-absorption effect has been observed. The detrimental role of the re-absorption has been explained by characterising the up-conversion spectrum at different fibre lengths.

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Contributors

Author: V. Scarnera

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