Enhanced 14 μm emissions of Tm³⁺ via Tb³⁺ deactivation in (Gd₀₅Lu₀₅)₂SiO₅ crystal

The use of Tb3+ codoping for the enhancement of the transition of Tm3+:3H4→3F4 ∼1.4 μm emissions was investigated in the Tm3+/Tb3+ codoped (Gd0.5Lu0.5)2SiO5 (Tm/Tb:GLSO) crystal for the first time. The ∼1.4 μm fluorescence emission properties and energy transfer mechanism of the as-grown crystals were investigated in detail. It is found that the codoped of Tb3+ ion in Tm/Tb:GLSO crystal greatly enhances Tm3+:1.4 μm emission under excitation of a common 789 nm laser diode, depopulates the lower laser level of Tm3+:3F4, and has little effect on the upper laser level of Tm3+:3H4 at the same time. The energy transfer efficiency from the Tm3+:3F4 level to the Tb3+:7F0 level is as high as (74.4±1.5)%, indicating that the Tb3+ ion is an effective deactivation ion for enhancing the ∼1.4 μm emission in Tm/Tb:GLSO crystal. These results suggest that Tm/Tb:GLSO crystal may be a promising material for ∼1.4 μm laser under the pump of a conventional 789 nm LD.