Nonlinear optical properties of MXene and applications in broadband ultrafast photonics

As a typical kind of two-dimensional transition metal carbides, nitrides and/or carbonitrides (MXene), Ti3C2Tx has attracted extensive attention in optoelectronic field owing to their outstanding thermal, optoelectronic, and nonlinear optical properties. Ti3C2Tx has been widely used as saturable absorber (SA) for achieving ultrafast pulses, whereas the influence of recovery time on its nonlinear optical properties as SA in laser needs further exploration. Herein, the ultrafast dynamics and nonlinear optical properties of Ti3C2Tx are investigated by the methods of transient absorption and balanced twin-detector measurements. According to the experimental results, Ti3C2Tx has a bleaching recovery time more than 160 ps, resulting in a low saturation intensity. The prepared Ti3C2Tx is utilized as SA to achieve Q-switched pulses at 1- and 1.5-μm bands. This study demonstrates that ultrafast dynamics has a significant impact on adjusting and optimizing nonlinear optical parameters of MXenes, as well as designing new photonic devices.