Ti₃C₂T_x MXene Quantum Dots with Surface-Terminated Groups (-F, -OH, =O, -Cl) for Ultrafast Photonics

Transition metal carbides and nitrides (MXenes) have attracted significant attention in photoelectric applications due to their highly tunable electronic and optical properties influenced by a flexible compositional or surface functional group regulation. Ti3C2Tx MXenes (-F, -OH, =O terminated) used in previous ultrafast photonic studies are usually synthesized via a generic hydrofluoric acid (HF) etching strategy, which may cause numerous defects and thus impedes the optoelectronic properties of Ti3C2Tx. In this contribution, inspired by a much higher conductivity and carrier mobility of Ti3C2Tx (-F, -OH, =O, -Cl terminated) prepared from a minimally intensive layer delamination method (MILD) etching strategy, we further optimized it with a liquid-phase exfoliation (LPE) method to synthesize pure Ti3C2Tx quantum dots (QDs) for ultrafast photonic. Compared to the other QDs saturable absorber (SA) devices performed at 1550 nm, our SA device exhibited a relatively low saturation intensity (1.983 GW/cm−2) and high modulation depth (11.6%), allowing for a more easily mode-locked pulse generation. A distinguished ultrashort pulse duration of 466 fs centered at the wavelength of 1566.57 nm with a fundamental frequency of 22.78 MHz was obtained in the communication band. Considering the SA based on such a Ti3C2Tx QDs tapered fiber is the first exploration of Er3+-doped fiber laser (EDFL), this work will open up a new avenue for applications in ultrafast photonics