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Ternary chalcogenide Ta2NiS5 as a saturable absorber for a 1.9  μm passively Q-switched bulk laser.

In this Letter, a high-quality saturable absorber (SA) based on a multilayered two-dimensional ternary chalcogenide Ta2NiS5 with a narrow bandgap, has been successfully fabricated and used as a SA in a 1.9 μm spectral region. The nonlinear saturable absorption properties of the as-prepared SA have been investigated by using an open-aperture Z-scan method. A passively Q-switched all-solid-state laser operating at 1.9 μm has been realized with the Ta2NiS5 SA. The maximum average output power, shortest pulse width, pulse energy, and pulse peak power from the passively Q-switched (PQS) laser are 1.1 W, 313 ns, 22.0 μJ, and 71.0 W, respectively. This is the first demonstration of the saturable absorption property of Ta2NiS5, to the best of our knowledge. The results indicate well the promising potential of Ta2NiS5 as a broadband SA in realizing pulsed mid-infrared lasers with high performance.