Spectroscopic properties and energy transfer in Nd3+/Yb3+ co-doped yttrium aluminum garnet

Abstract

High-quality Nd,Yb:YAG crystal with 5 at. % Yb3+ and 0.5 at. % Nd3+ was grown using the Czochralski method. A complete optical characterization was reported including absorption, excitation spectra and luminescence lifetime measurements at room temperature and emission spectra at temperatures ranging from 300 K to 800 K. The emission spectra of Nd3+/Yb3+ co-doped YAG were measured for different excitation wavelengths 808 nm and 940 nm. The presence of Yb3+ emission after excitation in the 4F5/2 and 4F3/2 levels of Nd3+ together with the 4I9/2→ 4F5/2 and 4I9/2→ 4F3/2 bands of Nd3+ in the excitation spectra of Yb3+ ions confirm that energy transfer occurs from Nd3+ to Yb3+. On the other hand, the back transfer from Yb3+ to Nd3+ can be neglected. This conclusion is also in agreement with the vanishing overlap between the Yb3+ emission and Nd3+ absorption. The analysis of the luminescence decay curves obtained after pulsed excitation has been used to further explore energy transfer processes and the interaction mechanism.