Tungsten disulfide coated microfiber as saturable absorber for Q-switched pulses generation

Q-switched fiber laser was demonstrated by using tungsten disulfide (WS₂) two-dimensional nanomaterials as a passive saturable absorber (SA) to modulate the loss inside the laser cavity. The SA was produced by repeatedly dropping and drying the WS₂ solution onto microfiber to form a nanosheets layer. The WS₂ coated microfiber is inserted into the ring laser cavity configured with a 2.4 m long Erbium-doped fiber (EDF) as the gain medium to generate Q-switching pulses train operating at 1568 nm. The Q-switched laser produced a pulse train, which the repetition rate is tunable from 62.0 kHz to 78.0 kHz as the pump power is raised from 151 to 193 mW. The minimum pulse width of 4.72 μs and the maximum pulse energy of 20.5 nJ was obtained at 193 mW pump power. The generated Q-switching pulses are stable and thus it is suitable for use in many practical applications.