Microfiber-based, highly nonlinear graphene saturable absorber for formation of versatile structural soliton molecules in a fiber laser

We reported on the generation of versatile soliton molecules in a fiber laser mode-locked by a microfiber-based graphene saturable absorber (GSA). By virtue of the highly nonlinear effect of the microfiber-based GSA, the soliton molecules could be easily observed. In addition to regular soliton molecules, it is found that the soliton atoms in molecules could exhibit different characteristics and show ultra-narrow pulse separations, which was termed as 'structural soliton molecule'. The pulse profiles of 'structural soliton molecules' were further reconstructed theoretically. The obtained results would give further insight towards understanding the dynamics of soliton molecules in fiber lasers. (C) 2014 Optical Society of America.