Two-dimensional (2D) ternary chalcogenides have attracted great attentions because of their novel chemical and physical properties arising from the synergistic effect and stoichiometric variation with the additional third element compared with their binary counterparts. Here, high-quality 2D tantalum nickel selenide (Ta₂NiSe₅) nanosheets are successfully fabricated by a liquid-phase exfoliation (LPE) method. The ultrafast excited carrier relaxation time and nonlinear optical absorption response are investigated and reveal that the prepared 2D Ta₂NiSe₅ nanosheets have excellent broadband saturable absorption properties, which are further illustrated by three passively Q-switched (PQS) all-solid-state lasers operating at 1.0, 2.0 and 2.8 µm with the Ta₂NiSe₅ nanosheet-based saturable absorber (SA). Furthermore, mode-locked laser operation with the pulse width as short as 356 fs is also realized at 1.0 µm. This work not only demonstrates the excellent nonlinear optical proprieties and optical modulation performance of Ta₂NiSe₅, but also paves the way for exploring the photonic and optoelectronic proprieties of ternary chalcogenide materials.

二维（2D）三元硫族化物因与其他二元硫化物相比具有附加的第三元素的协同​​作用和化学计量变化而具有新颖的化学和物理性质，因此备受关注。在这里，通过液相剥离（LPE）方法成功地制造了高质量的二维钽硒化镍镍（Ta ₂ NiSe ₅）纳米片。研究了超快激发载流子的弛豫时间和非线性光吸收响应，发现所制备的二维Ta ₂ NiSe ₅纳米片具有出色的宽带可饱和吸收性能，这进一步通过使用基于Ta ₂ NiSe ₅纳米片的可饱和吸收剂（SA）在1.0、2.0和2.8 µm下工作的三只被动Q开关（PQS）全固态激光器进一步说明。此外，在1.0 µm的波长下，也可实现脉冲宽度短至356 fs的锁模激光操作。这项工作不仅证明了Ta ₂ NiSe ₅的优异的非线性光学特性和光调制性能，而且为探索三族硫族化物材料的光子和光电特性铺平了道路。