Multimodal Nonlinear Optical Imaging of MoS2 and MoS2-Based van der Waals Heterostructures.

Dawei Li (1) , Wei Xiong (1, 2) , Lijia Jiang (1, 3) , Zhiyong Xiao (4) , Hossein Rabiee Golgir (1) , Mengmeng Wang (1) , Xi Huang (1) , Yunshen Zhou (1) , Zhe Lin (1) , Jingfeng Song (4) , Stephen Ducharme (4) , Lan Jiang (3) , Jean-François Silvain (5) , Yongfeng Lu (1)

1 Department of Electrical Engineering
2 Wuhan National Laboratory for Optoelectronics
3 School of Mechanical Engineering
4 Department of Physics and Astronomy
5 ICMCB - Institut de Chimie de la Matière Condensée de Bordeaux

van der Waals layered structures, notably the transitional metal dichalcogenides (TMDs) and TMD-based heterostructures, have recently attracted immense interest due to their unique physical properties and potential applications in electronics, optoelectronics, and energy harvesting. Despite the recent progress, it is still a challenge to perform comprehensive characterizations of critical properties of these layered structures, including crystal structures, chemical dynamics, and interlayer coupling, using a single characterization platform. In this study, we successfully developed a multimodal nonlinear optical imaging method to characterize these critical properties of molybdenum disulfide (MoS2) and MoS2-based heterostructures. Our results demonstrate that MoS2 layers exhibit strong four-wave mixing (FWM), sum-frequency generation (SFG), and second-harmonic generation (SHG) nonlinear optical characteristics. We believe this is the first observation of FWM and SFG from TMD layers. All three kinds of optical nonlinearities are sensitive to layer numbers, crystal orientation, and interlayer coupling. The combined and simultaneous SHG/SFG-FWM imaging not only is capable of rapid evaluation of crystal quality and precise determination of odd-even layers but also provides in situ monitoring of the chemical dynamics of thermal oxidation in MoS2 and interlayer coupling in MoS2-graphene heterostructures. This method has the advantages of versatility, high fidelity, easy operation, and fast imaging, enabling comprehensive characterization of van der Waals layered structures for fundamental research and practical applications.

Mots clés: Nonlinear optical imaging; transition metal dichalcogenides; van der Waals heterostructure; four-wave mixing; sum-frequency generation; second-harmonic generation; interlayer coupling

Domaines: Matériaux; Optique [physics.optics]

Dawei Li, Wei Xiong, Lijia Jiang, Zhiyong Xiao, Hossein Rabiee Golgir, et al.. Multimodal Nonlinear Optical Imaging of MoS2 and MoS2-Based van der Waals Heterostructures.. ACS Nano, 2016, 10 (3), pp.3766-3775. ⟨10.1021/acsnano.6b00371⟩. ⟨hal-01299527⟩