Giant All-Optical Modulation of Second-Harmonic Generation Mediated by Dark Excitons

Yadong Wang, Susobhan Das, Fadil Iyikanat, Yunyun Dai, Shisheng Li, Xiangdong Guo, Xiaoxia Yang, Jinluo Cheng, Xuerong Hu, Masood Ghotbi, Fangwei Ye, Harri Lipsanen, Shiwei Wu, Tawfique Hasan, Xuetao Gan, Kaihui Liu, Dong Sun, Qing Dai, F. Javier García De Abajo, Jianlin Zhao*Zhipei Sun

*Corresponding author for this work

Research output: Contribution to journalArticleScientificpeer-review

2 Citations (Scopus)
38 Downloads (Pure)

Abstract

All-optical control of nonlinear photonic processes in nanomaterials is of significant interest from a fundamental viewpoint and with regard to applications ranging from ultrafast data processing to spectroscopy and quantum technology. However, these applications rely on a high degree of control over the nonlinear response, which still remains elusive. Here, we demonstrate giant and broadband all-optical ultrafast modulation of second-harmonic generation (SHG) in monolayer transition-metal dichalcogenides mediated by the modified excitonic oscillation strength produced upon optical pumping. We reveal a dominant role of dark excitons to enhance SHG by up to a factor of ∼386 at room temperature, 2 orders of magnitude larger than the current state-of-the-art all-optical modulation results. The amplitude and sign of the observed SHG modulation can be adjusted over a broad spectral range spanning a few electronvolts with ultrafast response down to the sub-picosecond scale via different carrier dynamics. Our results not only introduce an efficient method to study intriguing exciton dynamics, but also reveal a new mechanism involving dark excitons to regulate all-optical nonlinear photonics.

Original languageEnglish
Pages (from-to)2320-2328
Number of pages9
JournalACS Photonics
Volume8
Issue number8
Early online date2021
DOIs
Publication statusPublished - 18 Aug 2021
MoE publication typeA1 Journal article-refereed

Keywords

  • Bright Excitons
  • Dark Excitons
  • Optically-Modulated Excitonic Strength
  • Second-Harmonic Generation
  • Transition Metal Dichalcogenides Monolayers
  • Ultrafast Optical Modulation

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