Tri-wavelength passively Q-switched Yb3+:GdAl3(BO3)4 solid-state laser based on WS2 saturable absorber

Using the WS2 nanosheets prepared by a facile hydrothermal reaction as saturable absorber (SA), we demonstrate a tri-wavelength passively Q-switching operation of a diode-pumped Yb:GdAl3(BO3)4 (Yb:GAB) crystal laser for the first time. The single pulse energy up to 1.30 μJ with the output power of 140 mW is obtained. The corresponding pulse width and repetition frequency rate are 440 ns and 107.8 kHz, respectively. The stable pulsed laser operates at 1044.9, 1045.6 and 1048.5 nm, simultaneously. This work suggests that solvothermal synthesized WS2 could be a promising SA to realize a simultaneously multi-wavelength laser operation.