2 µm passively Q-switched all-solid-state laser based on a Ta2NiSe5 saturable absorber

In this paper, a novel 2D ternary chalcogenide Ta2NiSe5 is fabricated into a saturable absorber by using the liquid phase exfoliation (LPE) method and successfully applied to the passive Q-switching experiment of Tm:YAP all-solid-state laser at 2 µm. The nonlinear optical absorption (NOA) properties of Ta2NiSe5 at 2 µm was measured by using an open-aperture Z-scan method, showing saturation fluence and modulation depth of 400 µJ/cm2 and 24%, respectively. By using Ta2NiSe5 as saturable absorber, the shortest pulse width of 740 ns and maximum repetition frequency of 71 kHz are obtained, respectively. This results prove that the Ta2NiSe5 is an excellent saturable absorber to achieve passively Q-switched laser at 2 µm, for the first time to the best of our knowledge.