Few-layer Ti3CN MXene for ultrafast photonics applications in visible band

Ti3CN, as a typical hetero-MXene, has attracted tremendous attention for its unique properties. However, its ultrafast photonics applications are still rare. Here, the few-layer Ti3CN MXene was successfully prepared by selective etching and molecular delamination technique. The nonlinear optical response of few-layer Ti3CN MXene at 640 nm was studied using the open-aperture Z-scan technique. The as-prepared Ti3CN MXene sample exhibited excellent nonlinear saturable absorption characteristics, resulting in the nonlinear absorption coefficient β of −4.05 × 10-2 cm/GW, which was one order of magnitude larger than that of black phosphorus (BP) and molybdenum disulfide (MoS2). For the optical modulation applications of few-layer Ti3CN MXene, passively Q-switched (PQS) solid-state visible lasers based on Ti3CN saturable absorber (SA) at 522 nm, 607 nm, 639 nm, and 721 nm were successfully realized. Furthermore, a Ti3CN-based stable passively mode-locked Pr:YLF red laser was also successfully achieved with a pulse duration of 30 ps, and the corresponding repetition rate was 73.1 MHz. The optical modulation device based on few-layer Ti3CN MXene shows good performance. Our work demonstrates that the tremendous prospects of the few-layer Ti3CN MXene as a visible optical modulation device in ultrafast photonics applications.