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

Abstract

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+: 2F5/2 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.

Praseodymium-Doped Nanoparticles: Candidates for Near-Infrared-II Double- and Single-Band Nanothermometry

“…To date, different types of materials and molecules have been examined for the design of luminescence nanothermometers, including organic dyes, quantum dots, polymers, and lanthanide (Ln)-based molecules, molecular cluster-aggregates, and nanoparticles. − Among them, Ln-based nanoparticles (Ln-NPs) have been widely investigated due to their demonstrated excellent photostability, relatively low toxicity, and capability to emit light in the ultraviolet (UV), visible, and near-infrared (NIR) spectral range when excited with NIR light (e.g., 980 or 808 nm), so-called upconversion . Of particular interest for biomedical applications is their capability to emit light of wavelengths longer than 1000 nm under NIR excitation (downshifting), thus matching the so-called NIR biological transparency windows (NIR-I: 650–950 nm, NIR-II: 1000–1350 nm, NIR-III: 1450–1900 nm). , The most commonly used NIR-emitting Ln 3+ ions are Nd 3+ (NIR-I/II), Ho 3+ (NIR-II), Tm 3+ (NIR-I/II/III), and Er 3+ (NIR-III). − On the other hand, Pr 3+ is well-known for its visible photoluminescence under NIR or UV excitation, − though its NIR emission remains largely underexplored at the nanoscale. ,− For potential biological applications, the NIR-II emission centered at ca. 1300 nm, ascribed to the Pr 3+ 1 G 4 → 3 H 5 transition, is of interest given the limited overlap with the water absorption band with a maximum at 1400–1500 nm .…”