Fig. 1. Schematic illustration of fabricating multi-layered MXene-Ti3C2Tx, mono-layered MXene-Ti3C2Tx, and MXene-Ti3C2Tx SA.

Fig. 2. (a) TEM image of the Ti3C2Tx nanosheets on a scale of 50 nm. (b) AFM image of few-layered Ti3C2Tx on a scale of 200 nm and the corresponding height profile. (c) HRTEM image of Ti3C2Tx nanosheets on a scale of 10 nm. (d) SEM images of Ti3C2Tx nanosheets on a scale of 5 μm and 600 nm (inset). (e) AFM image of multi-layered Ti3C2Tx nanosheets on a scale of 200 nm and the corresponding height profile. (f) Linear absorption spectrum of Ti3C2Tx powder.

Fig. 3. (a) Experimental setup of nonlinear absorption measurement at 2866 nm. (b) Reflectivity of the Ti3C2Tx sample as a function of pulse peak intensity.

Fig. 4. Schematic setup of the passively Q-switched Er3+-doped ZBLAN fiber laser based on the MXene-Ti3C2Tx SA.

Fig. 5. Q-switched pulse trains at the pump power of (a) 2.72 W and (b) 5.87 W, (c) Q-switched single-pulse waveforms at the pump power of 2.72 W and 5.87 W, and (d) optical and RF (inset) spectra of the Q-switched pulses at the pump power of 5.87 W.

Fig. 6. (a) Output power and single-pulse energy as functions of the pump power, (b) output powers and slope efficiencies of mid-infrared passively Q-switched fiber lasers with different 2D materials SAs (icons with squares: multi-mode; icons with circles: mode unknown; icons without framing: single mode), and (c) repetition rate and pulse width as functions of the pump power.