Passively Q-switched waveguide lasers based on two-dimensional transition metal diselenide.

We reported on the passively Q-switched waveguide lasers based on few-layer transition metal diselenide, including molybdenum diselenide (MoSe₂) and tungsten diselenide (WSe₂), as saturable absorbers. The MoSe₂ and WSe₂ membranes were covered on silica wafers by chemical vapor deposition (CVD). A low-loss depressed cladding waveguide was produced by femtosecond laser writing in a Nd:YAG crystal. Under optical pump at 808 nm, the passive Q-switching of the Nd:YAG waveguide lasing at 1064 nm was achieved, reaching maximum average output power of 115 mW (MoSe₂) and 45 mW (WSe₂), respectively, which are corresponding to single-pulse energy of 36 nJ and 19 nJ. The repetition rate of the Q-switched waveguide lasers was tunable from 0.995 to 3.334 MHz (MoSe₂) and 0.781 to 2.938 MHz (WSe₂), and the obtained minimum pulse duration was 80ns (MoSe₂) and 52 ns (WSe₂), respectively.