Abstract
Owing to their extraordinary physical and chemical properties, two-dimensional (2D) materials have aroused extensive attention and have been widely used in photonic and optoelectronic devices, catalytic reactions, and biomedicine. In particular, 2D materials possess a unique bandgap structure and nonlinear optical properties, which can be used as saturable absorbers in ultrafast lasers. Here, we mainly review the top-down and bottom-up methods for preparing 2D materials, such as graphene, topological insulators, transition metal dichalcogenides, black phosphorus, and MXenes. Then, we focus on the ultrafast applications of 2D materials at the typical operating wavelengths of 1, 1.5, 2, and 3 m. The key parameters and output performance of ultrafast pulsed lasers based on 2D materials are discussed. Furthermore, an outlook regarding the fabrication methods and the development of 2D materials in ultrafast photonics is also presented.
Highlights
Nanomaterials are ultrathin materials with at least one-dimensional size in nanometers in three-dimensional space [1,2]
molecular beam epitaxy (MBE) faces some challenges, such as high cost caused by the complex ultra-high vacuum system, slow speed caused by precise control, as well as limitations on the available materials and substrates caused by strict lattice matching constraints [28]
We introduced the principles, preparation processes, characteristics, and applications of mechanical exfoliation (ME), solution-processed methods, deposition methods, MBE, and other widely used methods
Summary
Nanomaterials are ultrathin materials with at least one-dimensional size in nanometers in three-dimensional space [1,2]. In the past few decades, nanomaterials have shown potential to be excellent SAs. Carbon nanotubes (CNTs) are a kind of onedimensional materials with simple preparation and high cost-effectiveness that have the key advantage of a high damage threshold [25,26,27]. Compared with artificial SAs, CNTs, and 3D materials, 2D materials are extensively used in ultrafast pulsed lasers as superior SAs owing to the excellent saturable absorption properties, tunable modulation depths, and broadband responses. 2D materials have gradually become a reliable choice of SAs for ultrafast pulse lasers due to their unique low dimensional physical characteristics, as well as the advantages of a wide working band, controllable modulation depth, and ultrafast relaxation time [42,43]. We discuss the state of the art and challenges, as well as the future development of
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