Open AccessMonolayer graphene saturable absorbers with strongly enhanced evanescent-field interaction for ultrafast fiber laser mode-locking
Author(s) -
Nam Hun Park,
Hwanseong Jeong,
Sun Young Choi,
Mi Hye Kim,
Fabıan Rotermund,
DongIl Yeom
Publication year - 2015
Publication title -
optics express
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.394
H-Index - 271
ISSN - 1094-4087
DOI - 10.1364/oe.23.019806
Subject(s) - materials science , graphene , optics , saturable absorption , fiber laser , ultrashort pulse , cladding (metalworking) , monolayer , mode locking , laser , optoelectronics , pulse duration , wavelength , nanotechnology , physics , metallurgy
We demonstrate an efficient all-fiber saturable absorber (SA) that evanescently interacts with a graphene monolayer. Strong nonlinear interaction between the graphene sheet and evanescent wave was realized in both experiments and numerical calculations by employing an over-cladding structure on high-quality monolayer graphene that uniformly covered the side-polished fiber. A passively mode-locked Er-doped fiber laser was built, including our in-line graphene SA, which stably generated ultrashort pulses with pulse duration of 377 fs at a repetition rate of 37.7 MHz. The corresponding 3-dB spectral bandwidth of the laser was measured to be 8.6 nm at the central wavelength of 1607.7 nm. We also experimentally observed that the spectral bandwidth and pulse duration of the laser output could be controlled by proper selection of the refractive index of the over-cladding material on the monolayer-graphene SA.