2 µm passively Q-switched all-solid-state laser based on a Ta 2 NiSe 5 saturable absorber

In this paper, a novel 2D ternary chalcogenide Ta 2 NiSe 5 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 Ta 2 NiSe 5 at 2 µm was measured by using an open-aperture Z-scan method, showing saturation fluence and modulation depth of 400 µJ/cm 2 and 24%, respectively. By using Ta 2 NiSe 5 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 Ta 2 NiSe 5 is an excellent saturable absorber to achieve passively Q-switched laser at 2 µm, for the first time to the best of our knowledge.