Nonlinear optical properties and ultrafast photonics of 2D BP/Ti3C2 heterostructures

Abstract Heterostructures comprising two-dimensional (2D) materials have attracted increasing attention in recent years due to their unique properties. Here, a 2D black phosphorous (BP)/MXene (Ti3C2) heterostructure is prepared by stacking BP and Ti3C2 using van der Waals forces. Ultraviolet–visible absorption spectra proved the excellent stability of the heterostructure in water and air. In addition, strong nonlinear properties (high modulation depth with small saturation intensity) are demonstrated through Z-scan measurements, indicating that the BP/Ti3C2 heterostructure has excellent potential as an optical switch. To illustrate the applicability of the BP/Ti3C2 heterostructure ultrafast photonics, its performance as a saturable absorber in an Er-doped mode-locked fiber laser is demonstrated, resulting in a 735 fs pulse duration at a center wavelength of 1559.8 nm. Furthermore, harmonic mode-locking was also achieved by increasing the pump power, yielding a peak repetition rate of 588 MHz. These results reveal that 2D BP/Ti3C2 heterostructures have significant potential application in ultrafast photonics.