High efficiency laser action in mildly doped Yb:LuYAG ceramics

We report the first laser oscillations of 5 at%, 10 at% and 20 at% Yb3+ doped LuYAG ceramic samples and their spectroscopic characterization. The maximum output power, 8.7 W at 1029 nm, is achieved by 10 at% sample. A slope efficiency as high as 90.1% is obtained from the 10 at% doped sample. To our knowledge, these are the highest laser slope efficiencies obtained so far for Yb3+ doped LuYAG ceramics. With the 20 at% doped ceramic the maximum output power was 7.2 W at 1047.6 nm with a corresponding slope efficiency of 47.4%, whereas a decrease of the output power is observed for absorbed pump power higher than 15.6 W, probably due to the appearance of a non-linear loss mechanism. Finally, we explored the tunability of the ceramics finding the broadest continuous tuning range (from 992 nm to 1060 nm, i.e. 68 nm), with 5 at% and 10 at%, while it decreases to 54 nm with 20 at%.