MXene Ti3C2Tx (T = F, O, or OH) saturable absorber for a 2 μm doubly Q-switched laser with AOM

Abstract MXene Ti3C2Tx (T = F, O, or OH) was fabricated by aqueous acid etching and liquid phase exfoliation method. Its appearance, the spectra and the saturated absorption characteristics were measured. By using MXene Ti3C2Tx as saturable absorber (SA) and an acousto-optic modulator (AOM), a doubly Q-switched Tm:LuAG laser at 2 μm waveband was realized. Under the incident pump power of 9.5 W at modulated repetition rate 1 kHz of AOM, the narrowest laser pulse width of 178 ns was obtained, corresponding to the highest pulse peak power of 1062 W. To our knowledge, this is the shortest pulse width and highest peak power obtained in the Q-switched lasers with MXene Ti3C2Tx as SA. In comparison to the singly Q-switched laser with only MXene Ti3C2Tx or AOM, the doubly Q-switched laser can generate shorter pulse width and higher peak power. The maximum compression ratio of pulse width 6.0 and the highest enhancement factor of peak power 205 were achieved. The experimental results show that MXene Ti3C2Tx is an excellent SA in 2 μm waveband laser system and the doubly Q-switched laser can compress pulse width and improve pulse peak power.