Characterising energy transfer upconversion in Nd-doped vanadates at elevated temperatures

The Energy Transfer Upconversion (ETU) macroparameter is measured for Nd-doped GdVO4 and YVO4 samples at temperatures ranging from Room Temperature (RT) to 450K, by means of a simple and automated z-scan technique. Furthermore, the ground state absorption cross section into the 2H9/2 +4F5/2 energy levels is characterised for both crystals over the same range of temperatures. The 808 nm π-polarisation absorption cross section is found to decrease from (58.6 ± 0.2) pm2 to (30.9 ± 0.6) pm2 for Nd:YVO4 and (54.0 ± 0.3) pm2 to (25.7 ± 0.5) pm2 for Nd:GdVO4, from RT to 450K. Over the same range the ETU coefficient decreases from (3.2 ± 0.7) 10−16cm3/s to (1.8 ± 0.4 10−16cm3/s and (5.0 ± 0.5) 10−16cm3/s to (3.4±0.2) 10−16cm3/s for 0.6 at. % and 1 at. % Nd:YVO4 respectively, and (3.3 ± 0.5) 10−16cm3/s to (0.8 ± 0.2) 10−16cm3/s and (5.5 ± 0.5) 10−16cm3/s to (3.1 ± 0.3) 10−16cm3/s for 0.5 at.% and 1.1 at.% Nd:GdVO4.