168 fs pulse generation from graphene-chitosan mode-locked fiber laser

We propose new graphene-chitosan solution as a saturable absorber for a mode-locked Erbium-doped fiber laser. We demonstrate stable, mode-locked operation with pulse as short as 168 fs, which are the shortest pulses generated from an Er-doped fiber laser with the use of graphene so far. Graphene-chitosan solution was obtained in soluble forms by the addition of the acetic acid. The ring laser is able to generate optical solitons centered at 1554 nm wavelength with 15.2 nm bandwidth and 63 MHz repetition rate.