The Saturable Absorbers Based on2DMaterials

Driven by the rapidly increasing demands on optical communication, industrial manufacturing, and healthcare applications, nonlinear optical materials with saturable adsorption (SA) have received extensive attention. The emerging two-dimensional (2D) materials provide ideal candidates for the nonlinear saturable absorbers, owing to their large modulation depth, giant nonlinear coefficient, low saturation intensity, and large third-order nonlinear susceptibility. The evolution of saturable absorbers made of 2D materials is outlined in this chapter. The molecular insight into the SA phenomenon in 2D materials is first provided. Then, the development of 2D SA families is summarized, followed by the progress in practical applications, including the 2D material-based mode-locked and Q-switched lasers in the nonlinear optics (NLO). Challenges and strategies to bring the novel 2D saturable absorbers to future applications are also discussed at the end.