Synthesis, spectroscopy, and efficient laser operation of mixed sesquioxide Tm:(Lu, Sc)2O3 transparent ceramics

A novel transparent 4.76 at.% Tm:(Lu2/3Sc1/3)(2)O-3 mixed sequioxide ceramic is synthesized by hot isostatic pressing (HIP) at 1800 degrees C / 195 MPa in an Ar atmosphere. Its structure is studied by scanning electron microscopy, X-ray diffraction, and Raman spectroscopy. The spectroscopic properties of the Tm3+ ion are described within the Judd-Ofelt theory, which resulted in intensity parameters of Omega(2) = 2.429, Omega(4) = 1.078 and Omega(6) = 0.653 [10(-20) cm(2)]. For the F-3(4) -> H-3(6) transition, the maximum stimulated-emission cross-section sSE is 7.15 x 10(-21) cm(2) at 1951 nm. The radiative lifetime of the 3F4 state is 4.01 ms. Under diode-pumping at 802 nm, a microchip Tm:(Lu, Sc)O-2(3) ceramic laser generated similar to 1 W at 2100 nm with a slope efficiency of 24%. The spectroscopic and laser properties of the Tm:(Lu, Sc)O-2(3) ceramic are compared with those of a Tm: LuScO3 single crystal. The ceramic exhibits very broad and flat gain cross sections, which is promising for ultrashort pulse generation. (C) 2017 Optical Society of America under the terms of the OSA Open Access Publishing Agreement