Comparison of MoS_2 nanosheets and hierarchical nanospheres in the application of pulsed solid-state lasers

We prepared multi-layered MoS2 nanosheets and hierarchical MoS2 nanospheres composed of ultrathin nanosheets via a facile hydrothermal method. The presence of excessive thiourea played a critical role in the formation of nanospheres. Both the passively Q-switched single- and dual-wavelength Yb3+:GdAl3(BO3)4 (Yb:GAB) laser were achieved by using the multi-layered nanosheets and hierarchical nanospheres as saturable absorbers (SAs). As far as we know, the saturable absorption characteristic of hierarchical nanospheres was reported for the first time. Compared with nanosheets, the as-prepared nanospheres SA exhibited improved saturable absorption property with shorter pulse width and higher pulse energy, which should be attributed to the unique hierarchical structure.