Transfer of an exfoliated monolayer graphene flake onto an optical fiber end face for erbium-doped fiber laser mode-locking

This paper presents, for the first time, the successful transfer of exfoliated monolayer graphene flake to the optical fiber end face and alignment to its core. By fabricating and optimizing a polymeric poly (methyl methacrylate) (PMMA) and polyvinyl alcohol (PVA) substrate, it is possible to obtain a contrast of up to 11% for green light illumination, allowing the identification of monolayer graphene flakes that were transferred to optical fiber samples and aligned to its core. With Raman spectroscopy, it is demonstrated that graphene flake completely covers the optical fiber core, and its quality remains unaltered after the transfer. The generation of mode-locked erbium-doped fiber laser pulses, with a duration of 672 fs, with a single-monolayer graphene flake as a saturable absorber, is demonstrated for the first time. This transfer technique is of general applicability and can be used for other two-dimensional (2D) exfoliated materials.