Enhanced and modulated visible luminescence of Pr3+:CaF2 crystal by co-doping R3+ (R=Y, Gd, Lu) ions

Abstract

A series of 0.6 at% Pr:CaF2-RF3 (R = Y3+, Gd3+, Lu3+) crystals have been successfully grown by the temperature gradient technique(TGT). The absorption spectra, fluorescence spectra, and fluorescence decay curves were measured and analyzed at room temperature. When the R3+ concentration is higher than a certain value, the diffraction peaks of Pr:CaF2-RF3 crystals were well indexed to the (Ca,Y)F2 phase. By co-doping R3+ ion (R=Y3+, Gd3+, Lu3+), the spectral performance of the crystals could be significantly improved and the function effect is also different. For 0.6 at% Pr, 28.5 at% Y:CaF2 crystal, the fluorescence lifetime of 3P0 energy level was fitted to be 45.46 µs, and the emission cross sections of 3P0→3H6 (605 nm), and 3P0→3F2 (641 nm) were calculated to be 1.78 × 10−20 cm2, and 4.61 × 10−20 cm2 with the full width at half (FWHM) of 20.1 nm and 6.8 nm, respectively. The 0.6 at% Pr, 28.5 at% Y:CaF2 crystal could be favorble laser medium for ultra-fast laser opreration at 605 nm and 641 nm. For 0.6 at% Pr, 18 at% Gd:CaF2 and 0.6 at% Pr, 10 at% Lu:CaF2 crystals, the spectral quality factors σem•τf of 3P0→3F2 transition (642 nm) were calculated to be 614.18 × 10−20 cm2•µs and 506.36 × 10−20 cm2•µs with the FWHM of 3.7 nm and 5.3 nm. All the results show that 0.6 at% Pr, 18 at% Gd:CaF2 and 0.6 at% Pr, 10 at% Lu:CaF2 crystals are promising gain media for high-efficiency visible laser output at 642 nm, which would compete with commercial Pr: YLF crystal in the future.