Enhance and modulated near-infrared luminescence of Tm3+:CaF2 crystal by co-doping Y3+ ions

Abstract

A series of 0.5 at.% Tm:Ca1-xYxF2+x (x = 0, 0.01, 0.04, 0.06, 0.08, 0.12) crystals have been successfully grown by the temperature gradient technique (TGT) method. The absorption spectra, fluorescence spectra, and fluorescence decay curves were measured and analyzed at room temperature. By comparison, it is found that when the concentration of Y3+ ions reaches 8 at.%, the absorption cross section corresponding to the 3H6→3H4 energy level is 2.56 × 10−21 cm2 at 793 nm, which is suitable for GaAlAs LD pumping. The J-O strength parameters Ω2, Ω4, and Ω6 were obtained. With the incorporation of Y3+ ions, the value of Ω4/Ω6 gradually increases. When the concentration of Y3+ ions reaches 8 at.%, the emission cross sections are 3.05 × 10−21 cm2 at 1476 nm, 2.56 × 10−21 cm2 at 2378 nm, and the full widths at half maximum (FWHM) are 76 nm and 195 nm, respectively. The fluorescence lifetime of 3H4 level, the upper level of 1.5 μm and 2.3 μm, is 1.05 ms, which is very beneficial for 1.5 μm and 2.3 μm laser.