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

✍ Scribed by V. Scarnera; B. Richards; A. Jha; G. Jose; C. Stacey

• Publisher: Elsevier Science
• Year: 2010
• Tongue: English
• Weight: 399 KB
• Volume: 33
• Category: Article
• ISSN: 0925-3467
• DOI: 10.1016/j.optmat.2010.08.006

✦ Synopsis

Yb 3+ -Tb 3+ and Yb 3+ -Tm 3+ -Tb 3+ 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 5 D 4 level of the terbium ions in these experiments; namely multi excited state absorption (MESA) and cooperative up-conversion (CU). While in the Yb 3+ -Tm 3+ -Tb 3+ samples both MESA and CU contribute simultaneously to the 5 D 4 :Tb 3+ population, in the Yb 3+ -Tb 3+ case a pure CU mechanism is responsible for the 5 D 4 :Tb 3+ 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.