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Nano Research

Article Title

Giant pattern evolution in third-harmonic generation of strained monolayer WS2 at two-photon excitonic resonance

Authors

Jing Liang, State Key Laboratory for Mesoscopic Physics and Frontiers Science Center for Nano-optoelectronics, School of Physics, Peking University, Beijing 100871, China;Academy for Advanced Interdisciplinary Studies, Collaborative Innovation Center of Quantum Matter, Peking University, Beijing 100871, China
He Ma, State Key Laboratory for Mesoscopic Physics and Frontiers Science Center for Nano-optoelectronics, School of Physics, Peking University, Beijing 100871, China;Academy for Advanced Interdisciplinary Studies, Collaborative Innovation Center of Quantum Matter, Peking University, Beijing 100871, China
Jinhuan Wang, School of Chemistry and Chemical Engineering, Beijing Institute of Technology, Beijing 100081, China
Xu Zhou, State Key Laboratory for Mesoscopic Physics and Frontiers Science Center for Nano-optoelectronics, School of Physics, Peking University, Beijing 100871, China
Wentao Yu, State Key Laboratory for Mesoscopic Physics and Frontiers Science Center for Nano-optoelectronics, School of Physics, Peking University, Beijing 100871, China
Chaojie Ma, State Key Laboratory for Mesoscopic Physics and Frontiers Science Center for Nano-optoelectronics, School of Physics, Peking University, Beijing 100871, China
Muhong Wu, State Key Laboratory for Mesoscopic Physics and Frontiers Science Center for Nano-optoelectronics, School of Physics, Peking University, Beijing 100871, China
Peng Gao, International Center for Quantum Materials, Electron Microscopy Laboratory, School of Physics, Peking University, Beijing 100871, China
Kaihui Liu, State Key Laboratory for Mesoscopic Physics and Frontiers Science Center for Nano-optoelectronics, School of Physics, Peking University, Beijing 100871, China;Academy for Advanced Interdisciplinary Studies, Collaborative Innovation Center of Quantum Matter, Peking University, Beijing 100871, China
Dapeng Yu, Shenzhen Institute for Quantum Science and Engineering, and Department of Physics, Southern University of Science and Technology, Shenzhen 518055, China

Keywords

two-dimensional materials, nonlinear optics, excitonic effects

Abstract

Strong geometrical confinement and reduced dielectric screening of two-dimensional (2D) materials leads to strong Coulomb interaction and eventually give rise to extraordinary excitonic effects, which dominates the optical and optoelectronic properties. For nonlinear 2D photonic or optoelectronic applications, excitonic effects have been proved effective to tune the light-matter interaction strength. However, the modulation of excitonic effects on the other aspect of nonlinear response, i.e., polarization dependence, has not been fully explored yet. Here we report the first systemic study on the modulation of excitonic effects on the polarization dependence of second and third harmonic generation (SHG and THG) in strained monolayer WS2 by varying excitation wavelength. We demonstrated that polarization-dependent THG patterns undergo a giant evolution near two-photon excitonic resonance, where the long-axis of the parallel component (originally parallel to the strain direction) has a 90° flip when the excitation wavelength increases. In striking contrast, no apparent variation of polarization-dependent SHG patterns occurs at either two- or three-photon excitonic resonance conditions. Our results open a new avenue to modulate the anisotropic nonlinear optical response of 2D materials through effective control of excitonic resonance states, and thus open opportunity for new designs and applications in nonlinear optoelectronic 2D devices.

Publisher

Tsinghua University Press

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