High-power, air-cooled Thulium doped fiber amplifier with 71% slope efficiency Mathias Lenski, Qian Xu, Ziyao Wang, Philipp Gierschke, César Jauregui and Jens Limpert EPJ Web Conf., 307 (2024) 02047 Published online: 18 October 2024 DOI: 10.1051/epjconf/202430702047