Performance of Q-Switched Fiber Laser Using Optically Deposited Reduced Graphene Oxide as Saturable Absorber

Graphene is one of the most attractive two-dimensional nanomaterials widely used as saturable absorber for pulsing laser, owing to its unique non-linear optical responses. However, fabrication and integration of graphene saturable absorber into a laser cavity involves complex processes and procedures. Mass production of graphene-based saturable absorbers requires simplification of the fabrication process with minimum material wastage. Reduced graphene oxide, a functionalized graphene, is found to have saturable absorption property as well. Comparatively, it is easier and more cost-effective to produce. On the other hand, optical deposition is a saturable absorber deposition technique that maximizes material utilization. In this work, commercially available reduced graphene oxide in N-methyl-2-pyrrolidone was used to fabricate a saturable absorber device via optical deposition, due to its simplicity and high efficacy. Optical pulse generation via Q-switching were successfully demonstrated with the optically deposited rGO-SA incorporated into a ring erbium-doped fiber laser. Pulse repetition rate of up to ~85.0 kHz and pulse durations as short as ~2.0 μs were achieved. Its performance as a saturable absorber in a Q-switched fiber laser is then compared with previous works. Comparatively, optically deposited rGO has a much lower Q-switched threshold and holds huge potential for mass production with maximum material utilization.