Praseodymium mid-infrared emission in AlF₃-based glass sensitized by ytterbium

Broadband emission was obtained over 2.6 to 4.1 μm (Pr³⁺: ¹G₄→³F₄, ³F₃) in AlF₃-based glass samples doped with different concentrations of praseodymium and 1 mol% ytterbium using a 976 nm laser pump. An efficient energy transfer process from Yb³⁺: ²F_5/2 to Pr³⁺: ¹G₄ was analyzed through emission spectra and fluorescence lifetime values. The absorption and emission cross-sections were calculated by Füchtbauer-Ladenburg and McCumber theories and a positive gain can be obtained when P>0.3. To the best of the authors' knowledge, this work represents the first report of broadband mid-infrared emission of Pr³⁺ in an AlF₃-based glass. The results show that praseodymium doped AlF₃-based glass sensitized by ytterbium could be a promising candidate for fiber lasers operating in mid-infrared region.