Generation of passively Q-switched ytterbium laser by using tungsten tri-oxide film absorber

This study experimentally demonstrates a Q-switched fibre laser using a new tungsten tri-oxide (WO3)-based saturable absorber (SA). Using the drop and casting approach, we managed to prepare a thin film that contained WO3 powders in polyvinyl alcohol. A small bit of the film was used to form an SA which was placed in a ytterbium-doped fibre laser cavity to generate a Q-switched laser. The laser, operating at 1063.78 nm, was realised at the threshold pump power of 85 mW with a repetition rate of 23.87 kHz and a pulse width of 5.56 μs. At the pump power of 147 mW, the laser produced the maximum pulse energy of 625 nJ, signal-to-noise ratio of 59 dB, the repetition rate of 39.79 kHz and pulse width of 2.37 μs. To the best of our knowledge, this is the first demonstration of using WO3 SA to generate the pulse laser in the 1 μm region.