All-fiber 2 mu m mode-locked thulium-doped fiber laser with the graphene oxide film

An all-fiber passively mode-locked thulium-doped fiber laser (TDFL) that uses a graphene oxide (GO) film as a saturable absorber (SA) is reported. Stable pulses with a center wavelength of 1920.8 nm are generated at a repetition rate of 17.3 MHz. The pulse spectral width is 3.4nm and the pulse duration is about 1.14 ps. Production of stable and robust pulses indicates that the GO SA material is suitable for generation of 2 m mode-locking pulses. Our GO-based TDFL can be used as a seed source for 2 m high-power pulsed fiber amplifiers and thus represent a considerable step towards practical applications of these lasers, such as special materials processing, medical diagnosis and mid-infrared supercontinuum generation. (C) 2017 Elsevier GmbH. All rights reserved.