7.28-W, High-Energy, Conductively Cooled, Q-Switched Tm,Ho:YLF Laser

A diode-side-pumped laser oscillator with a Tm,Ho:YLF rod conductively cooled to −80 °C was developed. A Q-switched pulse energy of 104 mJ was achieved at a pulse repetition frequency of 70 Hz, corresponding to an average output power of 7.28 W. In addition, the maximum Q-switched pulse energy of 125 mJ was obtained at 50 Hz. Even at the maximum output level, the beam quality factor $M^{\mathrm {\mathbf {2}}}$ was measured to be $\leq $ 1.5. To the best of our knowledge, this is the highest average output power reported for a 100-mJ-class Q-switched 2- $\mu \text{m}$ laser oscillator using a conductively cooled laser head.