Article Enhancing Resonant Second-Harmonic Generation in Bilayer WSe2 by Layer-Dependent Exciton-Polaron Effect

Soonyoung Cha ; Tianyi Ouyang ; Takashi Taniguchi SAMURAI ORCID (National Institute for Materials Science) ; Kenji Watanabe SAMURAI ORCID (National Institute for Materials Science) ; Nathaniel M. Gabor ; Chun Hung Lui

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Soonyoung Cha, Tianyi Ouyang, Takashi Taniguchi, Kenji Watanabe, Nathaniel M. Gabor, Chun Hung Lui. Enhancing Resonant Second-Harmonic Generation in Bilayer WSe2 by Layer-Dependent Exciton-Polaron Effect. Nano Letters. 2024, 24 (46), 14847-14853. https://doi.org/10.1021/acs.nanolett.4c04544

Description:

(abstract)

Two-dimensional (2D) materials serve as exceptional platforms for
controlled second-harmonic generation (SHG). Current approaches to SHG control
often depend on nonresonant conditions or symmetry breaking via single-gate control.
Here, we employ dual-gate bilayer WSe2 to demonstrate an SHG enhancement
concept that leverages strong exciton resonance and a layer-dependent exciton-polaron
effect. By selectively localizing injected holes within one layer, we induce exciton-
polaron states in the hole-filled layer while maintaining normal exciton states in the
charge-neutral layer. The distinct resonant conditions of these layers effectively break
interlayer inversion symmetry, thereby promoting resonant SHG. This method
achieves a remarkable 40-fold enhancement of SHG at minimal electric field, equivalent to conditions near the dielectric-breakdown threshold but using only ∼3% of the critical breakdown field. Our results highlight SHG sensitivity to carrier density and type, offering a new tool for manipulating SHG and probing quantum states in 2D excitonic systems.

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Keyword: second-harmonic generation (SHG)
, WSe2
, exciton-polaron


Date published: 2024-11-20

Publisher: American Chemical Society (ACS)

Journal:

  • Nano Letters (ISSN: 15306984) vol. 24 issue. 46 p. 14847-14853

Funding:

  • U.S. Department of Defense W911NF2110260
  • U.S. Department of Defense FA9550-20-1-0097
  • Ministry of Education, Culture, Sports, Science and Technology 19H05790
  • Ministry of Education, Culture, Sports, Science and Technology 20H00354
  • Ministry of Education, Culture, Sports, Science and Technology 21H05233
  • American Chemical Society 61640-ND6
  • National Science Foundation 1945660
  • ARO MURI W911NK-24-1-0292

Manuscript type: Publisher's version (Version of record)

MDR DOI:

First published URL: https://doi.org/10.1021/acs.nanolett.4c04544

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Updated at: 2026-02-10 12:30:14 +0900

Published on MDR: 2026-02-10 09:14:31 +0900

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