Intense 2.89 μm emission from Dy³⁺/Yb³⁺-codoped PbF₂ crystal by 970 nm laser diode pumping

A novel Dy(3+)/Yb(3+) co-doped PbF2 mid-IR laser crystal was successfully grown using the vertical Bridgman method. Efficient emission at around 3 μm from the crystal was observed under excitation of a conventional 970 nm laser diode (LD). The energy transfer efficiency from Yb(3+) to Dy(3+) in Dy(3+)/Yb(3+):PbF2 crystal is as high as (97.7±0.3)%. It is also found that the Dy(3+)/Yb(3+):PbF2 crystal possesses long fluorescence lifetime (15.4±0.2) ms, high quantum efficiency (95.0±0.3)%, and large emission cross section (1.37±0.11)×10(-20) cm2 corresponding to the stimulated emission of Dy(3+):(6)H(13/2)→(6)H(15/2) transition. Additionally, the phonon energy of the crystal was analyzed by the Raman spectrum. These results indicate that Dy(3+)/Yb(3+):PbF2 crystal may become a promising material for 3 μm solid state lasers under a conventional 970 nm LD pump.