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.