Type-II Weyl Semimetal NbIrTe₄ Nanosheets for High Signal-to-Noise Ratio Pulsed Laser Generation

The two-dimensional van der Waals layered topological material NbIrTe4 has attracted much attention as a type-II Weyl semimetal due to its high mobility, superconductivity, and excellent photoresponse. Here, we synthesized high-quality NbIrTe4 single crystals using the molten salt method and then obtained the corresponding nanosheets through mechanical exfoliation. Then, the morphology, chemical composition, and nonlinear optical characteristics of NbIrTe4 were thoroughly examined. The saturable absorption (SA) properties of NbIrTe4 were measured by using a balanced two-detector system, indicating a modulation depth of 28.3% and a saturation intensity of 8.5 μJ cm–2. Subsequently, we realized a nanoscale low-threshold pulsed laser based on NbIrTe4–SA, which consistently maintains a signal-to-noise ratio up to 50 dB across varying pump powers, and the pulse duration was as short as 2.8 μs. Our work expands the family of C-band pulsed lasers utilizing two-dimensional materials, paving the way for the application of NbIrTe4 nanosheets in nonlinear optics and photonics.