Nonlinear absorption-induced transparency and extinction of boron nanosheets

Abstract Two-dimensional (2D) materials exhibit interesting nonlinear optical properties, and they have been used in bioimaging, ultrafast photon and all-optical switch devices. Boron nanosheets is a recently emerging 2D material that has attracted the attention of a large number of researchers. In this work, the saturation absorption (SA) effect of boron nanosheets has been investigated through a typical z-scan method, it is demonstrated that the nonlinear absorption coefficient and the quality factor are greatly improved compared with the other 2D materials such as black phosphorus, MoS2 and Ti3C2Tx. By combining the all-optical modulation and z-scan technology, the competition between the laser intensity-dependent SA and nonlinear scattering in boron nanosheets are revealed, and hence the optically-induced transparency and optically-induced extinction in nanosecond regime have been confirmed. Based on this competitive effect, an effective modulation of continuous light (λ = 671 nm) by nanosecond pulses (λ = 532 nm) has been realized, the maximum modulation depth of 5.5 dB is obtained.