Ultrafast Nonlinear Optical Excitation Behaviors of Mono- and Few-Layer Two Dimensional MoS2
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The layered MoS2 has recently attracted significant attention for its excellent nonlinear optical properties. Here, the ultrafast nonlinear optical (NLO) absorption and excited carrier dynamics of layered MoS2 (monolayer, 3–4 layers, and 6–8 layers) are investigated via Z-scan and transient absorption spectra. Our experimental results reveal that NLO absorption coefficients of these MoS2 increase from–27 × 103 cm/GW to–11 × 103 cm/GW with more layers at 400-nm laser excitation, while the values decrease from 2.0 × 103 cm/GW to 0.8 × 103 cm/GW at 800 nm. In addition, at high pump fluence, when the NLO response occurs, the results show that not only the reformation of the excitonic bands, but also the recovery time of NLO response decreases from 150 ps to 100 ps with an increasing number of layers, while the reductive energy of A excitonic band decreases from 191.7 meV to 51.1 meV. The intriguing NLO response of MoS2 provides excellent potentials for the next-generation optoelectronic and photonic devices.
KeywordsUltrafast optics two-dimensional materials ultrafast photonic devices
This work was partially supported by Open Research Fund of Hunan Provincial Key Laboratory of High Energy Technology (Grant No. GNJGJS03) and Opening Foundation of State Key Laboratory of Laser Interaction with Matter (Grant No. SKLLIM1702).The authors also would like to thank OU Yanghao, Zhang Jun, and Chen Runze in NUDT (National University of Defense Technology) for their great contributions to the data-collection work.
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