Novel molybdenum disulfide Langmuir Blodgett thin film as a saturable absorber for a passively Q-switched Nd: GdVO₄ laser

We fabricated a molybdenum disulfide (MoS₂) saturable absorber (SA) by coating MoS2 thin film on a quartz plate with the Langmuir-Blodgett (LB) method. To the best of our knowledge, it is the first time that saturable absorbers have been fabricated with the LB method. The film thickness can be adjusted freely in the LB method process. In addition, the surface of the absorber film made by the LB method was very smooth, which can decrease the optical scattering on the absorber, thus reducing the non-saturable absorption losses. With such an absorber, higher average output power two-dimensional material absorber mode locked lasers are possible. In this paper, a stable passively Q-switched (QS) Nd:GdVO4 laser was realized. The shortest pulse duration was 269.2 ns with a repetition rate of 1.03 MHz. The corresponding highest average output power, single pulse energy, and peak power were 1.39 W (35.85% conversion efficiency), 1.35 μJ, and 5.01 W, respectively. Therefore, the LB method may be a good choice to make practical two-dimensional material absorbers.