title: WS2 mode-locked ultrafast fiber laser.
abstract: Graphene-like two dimensional materials, such as WS2 and MoS2, are highly anisotropic layered compounds that have attracted growing interest from basic research to practical applications. Similar with MoS2, few-layer WS2 has remarkable physical properties. Here, we demonstrate for the first time that WS2 nanosheets exhibit ultrafast nonlinear saturable absorption property and high optical damage threshold. Soliton mode-locking operations are achieved separately in an erbium-doped fiber laser using two types of WS2-based saturable absorbers, one of which is fabricated by depositing WS2 nanosheets on a D-shaped fiber, while the other is synthesized by mixing WS2 solution with polyvinyl alcohol, and then evaporating them on a substrate. At the maximum pump power of 600 mW, two saturable absorbers can work stably at mode-locking state without damage, indicating that few-layer WS2 is a promising high-power flexible saturable absorber for ultrafast optics. Numerous applications may benefit from the ultrafast nonlinear features of WS2 nanosheets, such as high-power pulsed laser, materials processing, and frequency comb spectroscopy.
authors.affiliation: Key Laboratory of Space Applied Physics and Chemistry, Ministry of Education; and Shaanxi Key Laboratory of Optical Information Technology, School of Science, Northwestern Polytechnical University, Xi'an 710072, China.
authors.forename: Dong
authors.initials: D
authors.lastname: Mao
authors.affiliation: Key Laboratory of Space Applied Physics and Chemistry, Ministry of Education; and Shaanxi Key Laboratory of Optical Information Technology, School of Science, Northwestern Polytechnical University, Xi'an 710072, China.
authors.forename: Yadong
authors.initials: Y
authors.lastname: Wang
authors.affiliation: Key Laboratory of Space Applied Physics and Chemistry, Ministry of Education; and Shaanxi Key Laboratory of Optical Information Technology, School of Science, Northwestern Polytechnical University, Xi'an 710072, China.
authors.forename: Chaojie
authors.initials: C
authors.lastname: Ma
authors.affiliation: Key Laboratory of Space Applied Physics and Chemistry, Ministry of Education; and Shaanxi Key Laboratory of Optical Information Technology, School of Science, Northwestern Polytechnical University, Xi'an 710072, China.
authors.forename: Lei
authors.initials: L
authors.lastname: Han
authors.affiliation: Key Laboratory of Space Applied Physics and Chemistry, Ministry of Education; and Shaanxi Key Laboratory of Optical Information Technology, School of Science, Northwestern Polytechnical University, Xi'an 710072, China.
authors.forename: Biqiang
authors.initials: B
authors.lastname: Jiang
authors.affiliation: Key Laboratory of Space Applied Physics and Chemistry, Ministry of Education; and Shaanxi Key Laboratory of Optical Information Technology, School of Science, Northwestern Polytechnical University, Xi'an 710072, China.
authors.forename: Xuetao
authors.initials: X
authors.lastname: Gan
authors.affiliation: Key Laboratory of Space Applied Physics and Chemistry, Ministry of Education; and Shaanxi Key Laboratory of Optical Information Technology, School of Science, Northwestern Polytechnical University, Xi'an 710072, China.
authors.forename: Shijia
authors.initials: S
authors.lastname: Hua
authors.affiliation: Key Laboratory of Space Applied Physics and Chemistry, Ministry of Education; and Shaanxi Key Laboratory of Optical Information Technology, School of Science, Northwestern Polytechnical University, Xi'an 710072, China.
authors.forename: Wending
authors.initials: W
authors.lastname: Zhang
authors.affiliation: Key Laboratory of Space Applied Physics and Chemistry, Ministry of Education; and Shaanxi Key Laboratory of Optical Information Technology, School of Science, Northwestern Polytechnical University, Xi'an 710072, China.
authors.forename: Ting
authors.initials: T
authors.lastname: Mei
authors.affiliation: Key Laboratory of Space Applied Physics and Chemistry, Ministry of Education; and Shaanxi Key Laboratory of Optical Information Technology, School of Science, Northwestern Polytechnical University, Xi'an 710072, China.
authors.forename: Jianlin
authors.initials: J
authors.lastname: Zhao