Near-infrared downconversion in Pr^3+/Yb^3+ co-doped boro-aluminosilicate glasses and LaBO_3 glass ceramics

We report on downconversion of one blue photon to two near-infrared (NIR) photons (~10000 cm−1) in Pr3+/Yb3+ co-doped SrO-La2O3-Al2O3-B2O3-SiO2 glasses and LaBO3 glass ceramics. The Pr3+ ions act as broadband spectral sensitizer in the spectral range of 415-505 nm. Energy transfer occurs subsequently from Pr3+ to Yb3+, followed by re-emission in the NIR spectral range. The transfer efficiency is indicated by the degree of decrease of Pr3+-related photoluminescence (PL) and PL lifetime of the 3P0 and 1D2 levels with increasing Yb3+ concentration. For the present case, we find an optimum dopant concentration of Yb2O3 of ~0.5 mol % for a Pr2O3 concentration of 1.0 mol %. A theoretical maximum of quantum efficiency of 183% is reached for 5 mol % of Yb2O3. PL characteristics (absorption cross section and emission lifetime) are further improved upon precipitation of crystalline LaBO3, where both Pr3+ and Yb3+ ions occupy La3+ sites with an assumedly statistical distribution and a high degree of partitioning.