Single crystals of yttrium aluminum borate co-doped with 5% thulium and 10-20% ytterbium demonstrate upconversion luminescence both in the red and in the blue. All spectral components of the upconversion luminescence originate from 1G4 thulium ion state. A cooperative upconversion mechanism with a nearly quadratic slope of the power dependence dominates in the studied pump power density range. The excitation spectra are asymmetric due to different contributions from the crystal field split components of ytterbium 7F7/2-7F5/2 transition. Optimal ytterbium doping for efficient upconversion is below 20%.
Bibliographical noteFunding Information:
The work was supported by the RFBR Grants 07-02-00704 and 10-02-00294 , Grants of the President of the Russian Federation for the support of leading scientific schools (nos. SS-1011.2008.2 and SS-3818.2008.3 ), grant no. RNP.126.96.36.19955 , and Projects 3.9.1 and 27.1 of, no. 5 of SB RAS .
- Crystal growth