Generation of bound state of solitons pulses with graphene in Erbium-doped fiber laser cavity

We report an observation of bound state soliton in passively mode-locked Erbium-doped fiber laser employing graphene film as a passive saturable absorber (SA). The SA was fabricated from the graphene flakes, which were obtained from electrochemical exfoliation process. The graphene flakes were embedded into polyethylene oxide (PEO) film and we integrated the film into a laser cavity to generate soliton pulses. A bound soliton with pulse duration of ∼ 1.04 ps was obtained at the pump power of 110.8 mW by carefully adjusting the polarization of the oscillating laser. The formation of bound soliton is due to the direct pulse to pulse interaction. The results show that the proposed graphene based SA offers a simple and cost efficient approach of generating bound soliton in mode-locked EDFL setup. (paper)