High Efficient Continuous-Wave Ho:YAG Laser Pumped by a Diode-pumped Tm:YLF Laser at Room Temperature

We present a high efficient continuous wave Ho:YAG laser pumped by a diode-pumped Tm:YLF laser with a Fabry--Perot etalon tuning at 1.91μm. The maximum output power reaches 7.2W when the absorbed pump power is 10.8W. The slope efficiency (relative to the absorbed power) is 74.1%, and the Tm:YLF to Ho:YAG optical conversion efficiency of 60%, then the diode-to-Holmium optical conversion efficiency achieved is 21.0%. The wavelength is 2090nm when the transmission of output coupler is larger than 20%. The beam quality factor is M²~1.15 measured by the travelling knife-edge method.