High-damage-resistant tungsten disulfide saturable absorber mirror for passively Q-switched fiber laser

In this paper, we demonstrate a high-damage-resistant tungsten disulfide saturable absorber mirror (WS₂-SAM) fabricated by magnetron sputtering technique. The WS₂-SAM has an all-fiber-integrated configuration and high-damage-resistant merit because the WS₂ layer is protected by gold film so as to avoid being oxidized and destroyed at high pump power. Employing the WS₂-SAM in an Erbium-doped fiber laser (EDFL) with linear cavity, the stable Q-switching operation is achieved at central wavelength of 1560 nm, with the repetition rates ranging from 29.5 kHz to 367.8 kHz and the pulse duration ranging from 1.269 μs to 154.9 ns. For the condition of the maximum pump power of 600 mW, the WS₂-SAM still works stably with an output power of 25.2 mW, pulse energy of 68.5 nJ, and signal-noise-ratio of 42 dB. The proposed WS₂-SAM configuration provides a promising solution for advanced pulsed fiber lasers with the characteristics of high damage resistance, high output energy, and wide tunable frequency.