Q-Switched Yb-Doped Fiber Ring Laser with a Saturable Absorber Based on a Graphene Polyvinyl Alcohol Film

We propose, design, and demonstrate a Q -switched ytterbium-doped fiber laser (YDFL) employing a thin graphene polyvinyl alcohol (PVA) film as a passive saturable absorber (SA). The graphene is synthesized by electrochemical exfoliation of graphite at room temperature in 1% sodium dodecyl sulfate (SDS) aqueous solution. Graphene flakes obtained from the process are mixed with PVA solution as the host polymer to produce a thin film, which acts as a passive Q -switcher in the YDFL ring cavity. The laser generates a stable pulse operating at a wavelength of 1,076.4 nm with a threshold pump power of 73.7 mW. At a maximum 980 nm pump power of 113.6 mW, the YDFL generates an optical pulse train with a repetition rate of 25.53 kHz and a pulse width of 10 μ s. The maximum pulse energy of 50.9 nJ is obtained at a pump power of 109.9 mW. A higher-performance Q -switched YDFL is expected to be achieved with optimization of the graphene saturable absorber and the laser cavity.