Activation and deactivation effects to Ho^3+ at ~28 μm MIR emission by Yb^3+ and Pr^3+ ions in YAG crystal

The use of Yb3+ and Pr3+ co-doping with Ho3+ to enhance the Ho3+: I-5(6)-> I-5(7)similar to 2.8 mu m emissions are investigated in the YAG crystal for the first time. Absorption spectra of the Yb:Ho:YAG and Yb:Ho:Pr:YAG crystals find that doping of Yb3+ increase absorption intensity within 850-1050nm and make the crystals suitable to high-power InGaAs LDs. Fluorescence spectra show that similar to 2.8 mu m lasers may be realized on both crystals at different wavelengths, with the maximum emission cross section of 1.69 x 10(-20) cm(2) at 2780 nm for Yb: Ho: Pr: YAG and 1.23 x 10(-20) cm(2) at 2848 nm for Yb: Ho: YAG. Lifetime results and energy transfer analyses indicate that activator Yb3+ ions can prolong the higher laser level of Ho3+: I-5(6) and deactivator Pr3+ ions are able to depopulate the lower laser level of Ho3+: I-5(7), both beneficial to population inversion and contributed to facilitate similar to 2.8 mu m laser operations. All these results indicate that Yb: Ho: Pr: YAG crystal is a promising laser medium for LD-pumped similar to 2.8 mu m laser applications. (C) 2016 Optical Society of America