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Sternbach AJ, Latini S, Chae S, Hübener H, De Giovannini U, Shao Y, Xiong L, Sun Z, Shi N, Kissin P, Ni GX, Rhodes D, Kim B, Yu N, Millis AJ, Fogler MM, Schuck PJ, Lipson M, Zhu XY, Hone J, Averitt RD, Rubio A, Basov DN. Femtosecond exciton dynamics in WSe 2 optical waveguides. Nat Commun 2020; 11:3567. [PMID: 32678086 PMCID: PMC7367278 DOI: 10.1038/s41467-020-17335-w] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2020] [Accepted: 06/17/2020] [Indexed: 11/29/2022] Open
Abstract
Van-der Waals (vdW) atomically layered crystals can act as optical waveguides over a broad range of the electromagnetic spectrum ranging from Terahertz to visible. Unlike common Si-based waveguides, vdW semiconductors host strong excitonic resonances that may be controlled using non-thermal stimuli including electrostatic gating and photoexcitation. Here, we utilize waveguide modes to examine photo-induced changes of excitons in the prototypical vdW semiconductor, WSe2, prompted by femtosecond light pulses. Using time-resolved scanning near-field optical microscopy we visualize the electric field profiles of waveguide modes in real space and time and extract the temporal evolution of the optical constants following femtosecond photoexcitation. By monitoring the phase velocity of the waveguide modes, we detect incoherent A-exciton bleaching along with a coherent optical Stark shift in WSe2. The authors use time-resolved scanning near-field optical microscopy to probe the ultrafast excitonic processes and their impact on waveguide operation in transition metal dichalcogenide crystals. They observe significant modulation of the complex index by monitoring waveguide modes on the fs time scale, and identify both coherent and incoherent manipulations of WSe2 excitonic resonances.
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Affiliation(s)
- Aaron J Sternbach
- Department of Physics, Columbia University, New York, NY, 10027, USA.
| | - Simone Latini
- Max Planck Institute for the Structure and Dynamics of Matter, Luruper Chaussee 149, 22761, Hamburg, Germany
| | - Sanghoon Chae
- Department of Mechanical Engineering, Columbia University, New York, NY, 10027, USA
| | - Hannes Hübener
- Max Planck Institute for the Structure and Dynamics of Matter, Luruper Chaussee 149, 22761, Hamburg, Germany
| | - Umberto De Giovannini
- Max Planck Institute for the Structure and Dynamics of Matter, Luruper Chaussee 149, 22761, Hamburg, Germany
| | - Yinming Shao
- Department of Physics, Columbia University, New York, NY, 10027, USA
| | - Lin Xiong
- Department of Physics, Columbia University, New York, NY, 10027, USA
| | - Zhiyuan Sun
- Department of Physics, Columbia University, New York, NY, 10027, USA
| | - Norman Shi
- Department of Physics, Columbia University, New York, NY, 10027, USA
| | - Peter Kissin
- Department of Physics, University of California, San Diego, La Jolla, 92093, CA, USA
| | - Guang-Xin Ni
- Department of Physics, Columbia University, New York, NY, 10027, USA
| | - Daniel Rhodes
- Department of Mechanical Engineering, Columbia University, New York, NY, 10027, USA
| | - Brian Kim
- Department of Mechanical Engineering, Columbia University, New York, NY, 10027, USA
| | - Nanfang Yu
- Department of Physics, Columbia University, New York, NY, 10027, USA
| | - Andrew J Millis
- Department of Physics, Columbia University, New York, NY, 10027, USA
| | - Michael M Fogler
- Department of Physics, University of California, San Diego, La Jolla, 92093, CA, USA
| | - Peter J Schuck
- Department of Mechanical Engineering, Columbia University, New York, NY, 10027, USA
| | - Michal Lipson
- Department of Electrical Engineering, Columbia University, New York, NY, 10027, USA
| | - X-Y Zhu
- Department of Chemistry, Columbia University, New York, NY, 10027, USA
| | - James Hone
- Department of Mechanical Engineering, Columbia University, New York, NY, 10027, USA
| | - Richard D Averitt
- Department of Physics, University of California, San Diego, La Jolla, 92093, CA, USA
| | - Angel Rubio
- Max Planck Institute for the Structure and Dynamics of Matter, Luruper Chaussee 149, 22761, Hamburg, Germany.,Center for Computational Quantum Physics (CCQ), Flatiron Institute, 162 Fifth Avenue, New York, NY, 10010, USA
| | - D N Basov
- Department of Physics, Columbia University, New York, NY, 10027, USA
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