Design and modeling of a passively Q-switched diode-pumped Thulium laser at 2.3 μm

We report on a diode-pumped Tm:LiYF4 laser operating on the H-3(4) -> H-3(5) transition (at similar to 2.3 mu m) passively Q-switched by a Cr2+:ZnSe saturable absorber. This laser delivers a maximum average output power of 130 mW at 2304.6 nm with a nearly diffraction limited beam, a linear polarization (pi) and no colasing at similar to 1.9 mu m. The corresponding pulse characteristics (duration/energy) are 1.24 mu s/3.6 mu J at a repetition rate of 36 kHz. By power scaling under quasi-CW pumping, even shorter pulse durations of 870 ns and higher pulse energies of 6.1 mu J are achieved. The performance of the laser is simulated using a model of a quasi-four-level gain medium and a slow saturable absorber showing a good agreement with the experiment. The effect of the thermal lens of the saturable absorber on the pulse characteristics is discussed.

Automated summary

The diode-pumped Tm:LiYF4 laser, passively Q-switched by a Cr2+:ZnSe saturable absorber, achieves a maximum average output power of 130 mW at 2304.6 nm with nearly diffraction limited beam and pulse characteristics of 1.24 µs/3.6 µJ. By power scaling under quasi-CW pumping, shorter pulse durations of 870 ns and higher pulse energies of 6.1 µJ are achieved.