▎ 摘　　要

We demonstrate an L-band passively mode-locked erbium-doped fiber laser emitting at 1599.43 nm wavelength at a pulse train of 5.68 MHz. The microfiber reduced graphene oxide composite behaves as a saturable absorber that was fabricated using in-situ wet chemical and dip-coating methods. During operation, a single-pulse soliton was observed at a mode-locking threshold of 40 mW. This is a few times lower than most of the previous assessments in the same class of wavelength band and graphene saturable absorbers. The pulse duration was 568 fs with a maximum average output power of 6.75 mW. In addition, the superiority of this simple fabrication method facilitates its potential of mass production for applications in ultrafast photonics industries. (C) 2020 Optical Society of America under the terms of the OSA Open Access Publishing Agreement