High-Power 2.09µm Tm,Ho:YAG Laser: A Review of Recent Developments

In 1987, Kintz et al. demonstrated the successful operation of a room temperature Tm,Ho:YAG laser pumped by LDs, achieving an output power greater than 2mW [12]. In 1993, Bowman conducted a study on the performance of a side-pumped Tm,Ho:YAG laser with varying dopant concentrations of the crystal. However, he only obtained an average output power of 7.6W [13] due to detrimental up-conversion losses. Until 2014, Zhang Chao et al. employed two side-pumped laser modules with Tm:YAG and Tm,Ho:YAG in the same cavity, which generated a continuous wave (cw) output power of 37W at 2.1µm [14]. This is the highest 2.09µm output power achieved so far with co-doped Tm,Ho:YAG. However, the optical-to-optical efficiency for this system is only 3.1%.