11  W YLF-based intra-cavity pumped Ho laser with near diffraction limited beam quality

We develop a fluoride-based intra-cavity pumped Ho laser for the first time, where the severe thermal lensing of the intra-cavity pumping mechanism can be compensated by the negative thermal-optical property of the YLiF₄ (YLF) host. A maximum output power of 11.3 W (π-pol) at 2062 nm, corresponding to a conversion efficiency of 28.2% from the incident diode laser to the Ho laser, was obtained with a power instability below 0.5% and a near diffraction limited beam quality with M² of 1.06 and 1.25 in the horizontal and vertical directions, respectively. These are the maximum power and the best beam quality for the reported compact intra-cavity pumped Ho lasers, to the best of our knowledge.