Ti₃C₂T_xNanosheets for High-Repetition-Rate Wideband-Tunable Q-Switched Fiber Laser around 3 μm

We report a wavelength-tunable high-repetition-rate passively Q-switched fluoride fiber laser around 3μ m by using Ti3C2Tx MXene as saturable absorber (SA). The Ti3C2Tx MXene was synthesized by selectively etching aluminum layers in Ti3AlC2. The modulation depth, non-saturation loss and saturation fluence of the SA at 2866 nm were measured to be 43.10%, 25.16%, and 0.50 mJ/cm2, respectively. By introducing the Ti3C2Tx SA into a Ho3+/Pr3+-codoped fluoride fiber, stable Q-switched pulses with a continuously tuning range of 30.8 nm (2868.4 nm-2899.2 nm) were achieved. The repetition rate was as high as 215.3 kHz with an output power of 142 mW at the wavelength of 2879.0 nm. Such compact mid-infrared Q-switched laser source with a high repetition rate is of great importance in various applications such as medicine, high-resolution photoacoustic microscopy, and remote sensing. Our work indicates that the Ti3C2Tx MXene is a promising broadband light modulator for pulsed laser sources around 3μ m.