Bandwidth enhancement of ∼3 μm emission and energy transfer mechanism in Yb3+/Ho3+/Dy3+ co-doped PbF2 crystal

Abstract The ∼3 μm emission in Yb 3+ /Ho 3+ /Dy 3+ doped with PbF 2 crystal is investigated in this paper. The involved energy transfer mechanisms between Yb 3+ /Ho 3+ /Dy 3+ in PbF 2 crystal is explained in detail. As far as we know, it is the first time to report a broadband emission extending from about 2600 to 3400 nm with a maximum full width at half maximum (FWHM) of 283 nm obtained in Yb 0.02 Ho 0.02 Dy 0.02 : Pb 0.94 F 2 crystal under 970 nm pump. The energy transfer efficiency from Ho 3+ : 5 I 7 to Dy 3+ : 6 H 13/2 is as high as 97.9%, and the Ho 3+ : 5 I 6 → 5 I 7 fluorescence lifetime ratio τ( 5 I 6 )/τ( 5 I 7 ) in the Yb 0.02 Ho 0.02 Dy 0.02 : Pb 0.94 F 2 crystal was calculated to be 105.1%, indicating that Dy 3+ ion is to be an efficient deactivated ion for Ho 3+ ion to greatly facilitate the Ho 3+ : 5 I 6 → 5 I 7 , while also broaden the mid-infrared lasers operating in the wavelength region ∼3 μm. All imply that Yb 0.02 Ho 0.02 Dy 0.02 : Pb 0.94 F 2 crystal can be a potential candidate for the development of solid-state lasers operating in the mid-infrared broadband emission.