Ti3C2Tx Nanosheets 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 3 μm by using Ti
₃
C
₂
T
_x
MXene as saturable absorber (SA). The Ti
₃
C
₂
T
_x
MXene was synthesized by selectively etching aluminum layers in Ti
₃
AlC
₂
. 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 /cm
²
, respectively. By introducing the Ti
₃
C
₂
T
_x
SA into a Ho
³⁺
/Pr
³⁺
-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 Ti
₃
C
₂
T
_x
MXene is a promising broadband light modulator for pulsed laser sources around 3 μm.