Two-Dimensional Violet Phosphorus Nanosheets with Excellent Nonlinear Optical Properties for Ultrafast Lasers and Laser Protection

The violet phosphorus is a layered semiconductor material possessing a diverse range of exceptional physical properties. Until now, the nonlinear optical properties of violet phosphorus nanomaterials have been relatively scarce, and most of them were limited in the exploration of one single wavelength. In contrast, our study was based on the broadband nonlinear absorption characteristics of violet phosphorus nanomaterials from the ultraviolet to near-infrared waveband. In this paper, the two-dimensional violet phosphorus nanosheets were prepared by using the liquid-phase exfoliation method. The broadband (from ultraviolet to near-infrared) nonlinear optical properties of the two-dimensional violet phosphorus nanosheets were investigated by the open-aperture Z-scan method. And the band gap values of the two-dimensional violet phosphorus were analyzed through experimental characterization and density-functional theory. The experimental results show that the two-dimensional VP nanosheets exhibit saturable and two-photon absorption. In the ultraviolet band, the two-dimensional violet phosphorus nanosheets exhibit the most excellent saturable absorption properties. This work had important implications in the fields of ultrafast lasers, microfabrication, nanofabrication, and optical limiting fields.