Graphene-oxide-based Q-switched fiber laser with stable five-wavelength operation

We demonstrate an erbium-doped ring-cavity fiber laser Q-switched by a graphene oxide-based saturable absorber (GOSA). The GOSA was fabricated by vertically evaporating GO-polyvinylalcohol (GO/PVA) composite dispersion, and has a good performance under room temperature. Utilizing a specially fabricated fiber Bragg grating (FBG), stable five-wavelength lasing is realized and stabilized at different pump powers under any polarization state. When the pump power increases from 78.4 mW to 379.3 mW, the output power ranging from 1.9 mW to 16.6 mW could be obtained, with pulse duration from 6.8 μs to 2.72 μs, single pulse energy from 123.73 nJ to 229.74 nJ, and pulse repetition rate from 15.36 kHz to 72.25 kHz. To the best of our knowledge, it is the first simultaneous realization of five-wavelength operation and pulse output in a GO Q-switched all fiber laser system.