Ho:YAG laser at 2097 nm pumped by a narrow linewidth tunable 1.91 μm laser

This study presents a high efficiency Ho:YAG laser based on a narrow linewidth tunable 1.91 μm laser. A tunable Tm:YLF laser is the pump source and the wavelength continuous tunability ranges from 1906.04 to 1908.83 nm, corresponding to a linewidth of less than 0.41 nm. The tunable Tm:YLF laser is achieved by changing the operating temperature of the VBG. The output power of the Ho:YAG laser is between 21.04 and 23.53 W and the slope efficiency is between 64.08 and 68.26% at the pump power of 39.8 W. The output power and slope efficiency corresponding to the pump wavelength of 1907.36 nm are 23.53 W and 68.26%, respectively. This study illustrates that fine-tuning the pump wavelength is an effective way to improve the slope efficiency and output power of the Ho:YAG laser at room temperature.