Fs-laser-written thulium waveguide lasers Q-switched by graphene and MoS2

We report the generation of mid-infrared (similar to 2 mu m) high repetition rate (MHz) sub-100 ns pulses in buried thulium-doped monoclinic double tungstate Crystalline waveguide lasers using two-dimensional saturable absorber materials, graphene and MoS2. The waveguide (propagation losses of similar to 1 dB/cm) was micro-fabricated by means of ultrafast femtosecond laser writing. In the continuous-wave regime, the waveguide laser generated 247 mW at 1849.6 rim with a slope efficiency of 48.7%. The laser operated at the fundamental transverse mode with a linearly polarized output. With graphene as a saturable absorber the pulse characteristics were 88 ns / 18 tri (duration / energy) at a repetition rate of 1.39 MHz. Even shorter pulses of 66 ns were achieved with MoS2 Graphene and MoS2 are therefore promising for high repetition rate nanosecond Q-switched infrared waveguide lasers. (C) 2019 Optical Society of America under the terms of the OSA Open Access Publishing Agreement