Spectroscopic properties and pulsed laser performance of thulium-doped (Lu,Y)3Al5O12 mixed crystal

Abstract In this paper, we describe a thulium-doped (Lu,Y)3Al5O12 mixed crystal that was designed and grown to achieve a large pulse energy in Q-switched laser operation. Its absorption cross-sections at 781.3 nm and 1629.2 nm were calculated to be 3.4 × 10−21 cm2 and 5 × 10−21 cm2, respectively, and the emission cross-section at 2018.3 nm was calculated to be 1.92 × 10−21 cm2. The highest single pulse energy of 1.4 mJ near 2.02 μm was realized in an actively Q-switched solid-state laser, and further power scaling was just limited by the damage of the crystal coating. Based on the calculated spectrum parameters, theoretical simulation of the single pulse energy that considering the cross-relaxation process was proposed, which was well consistent with the experimental results.