The influence of Tm3+ to enhance 2.7 mu m mid-infrared emission of Er3+ in CaLaGa3O7 crystal

Er3+/Tm3+:CaLaGa3O7 (abbr. as Er3+/Tm3+:CLGO) crystal was grown successfully by Czochralski technology and detailed spectroscopic analyses were carried out. The effects of Tm3+ on the spectroscopic properties and mutual energy transfer mechanisms were investigated. It is found that the more suitable pumping scheme for laser applications at 2.7 mu m laser is 980 nm excitation for Er3+/Tm3+ co-doped CLGO crystal. Under 980 nm excitation, the introductions of Tm3+ are helpful to achieve enhanced mid-infrared (MIR) emissions, as well as reduced near-infrared emissions. Furthermore, the introducing Tm3+ depopulated the lower laser lever through energy transfer and thus reduced the fluorescence lifetime of Er3+ : I-4(13/2), without significantly affecting the fluorescence lifetime of the upper laser level Er3+ : I-4(11/2), which reduces the self-saturation problem to a great degree. It concludes that this Er3+/Tm3+:CLGO crystal could be a potential MIR gain media for enhanced 2.7 mu m laser under 980 nm pumping.