Open AccessZ-scan measurement of the nonlinear refractive index of monolayer WS_2
Author(s) -
Xin Zheng,
Yangwei Zhang,
Runze Chen,
Xina Cheng,
Zhongjie Xu,
Tian Jiang
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.23.015616
Subject(s) - materials science , femtosecond , refractive index , z scan technique , saturable absorption , optics , monolayer , absorption (acoustics) , two photon absorption , nonlinear optics , laser , tungsten disulfide , optoelectronics , wavelength , nanotechnology , fiber laser , physics , metallurgy , composite material
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 coecient was estimated about (3.7±0.28)×10(-6)m/W.