Q-switched double-clad Ytterbium-doped fiber laser using MoS₂ flakes saturable absorber

By sandwiching MoS₂ thin flakes between two fiber ferrule connectors in the ring cavity, we successfully demonstrate the passive Q-switched fiber laser operation. The cavity consists of all-fiber double-clad ytterbium-doped fiber (YDF) as a gain medium and MoS₂ tape as a saturable absorber (SA). The SA was prepared from a commercial MoS₂ crystal (~ 99.8 % purity) through mechanical exfoliation process. A piece of 1 mm x 1 mm tape contains MoS₂ thin flakes was sandwiched between two fiber connectors. By controlling loss and gain in the cavity, stable Q-switching operation were generated. The repetition rate was tunable from 4.8 kHz to 17.2 kHz as the pump power is varied from 753 mW to 1133 mW. The obtained pulse width is also narrowed from 21.3 µs to 10.44 µs with the same variation of pump power.