title: Z-scan measurement of the nonlinear refractive index of monolayer WS(2).
abstract: Transition metal dichalcogenides (TMDCs), such as tungsten disulfide (WS(2)), are layered materials with strong in-plane bonding and weak out-of-plane interactions enabling exfoliation into two-dimensional layers of single unit cell thickness. Recent advances in nanoscale materials characterization and few layer TMDCs' unique optical properties make them a research hot-spot in nonlinear optics. In this work, the nonlinear refractive index of monolayer WS(2) has been characterized with Z-scan measurement under 800nm femtosecond pulsed laser excitation, and a value of n2 ≃ (8.1 ± 0.41) × 10(-13)m(2)/W is obtained. A shift from saturable absorption to reverse saturable absorption was observed at higher input pump intensities in the experiments. The transition process was analyzed using a phenomenological model based on two photon absorption, and the two photon absorption coeﬃcient was estimated about (3.7±0.28)×10(-6)m/W.
authors.forename: Xin
authors.initials: X
authors.lastname: Zheng
authors.forename: Yangwei
authors.initials: Y
authors.lastname: Zhang
authors.forename: Runze
authors.initials: R
authors.lastname: Chen
authors.forename: Xiang'ai
authors.initials: X
authors.lastname: Cheng
authors.forename: Zhongjie
authors.initials: Z
authors.lastname: Xu
authors.forename: Tian
authors.initials: T
authors.lastname: Jiang