Tm,Ho:YAG Laser Efficiency: Balancing Dopant Concentration for Optimal Performance

The crucial factor limiting the high output power and efficient operation of Tm,Ho:YAG lasers is the unfavorable up-conversion loss, which strongly depends on dopant concentration. Typically, the dopant concentrations of Tm3+ and Ho3+ range from 4% to 6% and 0.3% to 1.5%, respectively. However, high Tm3+ concentration leads to excessive heat generation due to the linearly dependent up-conversion processes, which compromises laser performance, especially under intense pumping. Therefore, while high dopant concentration ensures high absorption efficiency and efficient cross-relaxation, it has few disadvantages and should be carefully considered.