Chiral Second-Harmonic Generation from Monolayer WS2/Aluminum Plasmonic Vortex Metalens

Wan Ping Guo, Wei Yun Liang, Chang Wei Cheng, Wei Lin Wu, Yen Ting Wang, Quan Sun, Shuai Zu, Hiroaki Misawa, Pi Ju Cheng, Shu Wei Chang, Hyeyoung Ahn*, Minn Tsong Lin*, Shangjr Gwo*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

2 Scopus citations

Abstract

Two-dimensional spiral plasmonic structures have emerged as a versatile approach to generate near-field vortex fields with tunable topological charges. We demonstrate here a far-field approach to observe the chiral second-harmonic generation (SHG) at designated visible wavelengths from a single plasmonic vortex metalens. This metalens comprises an Archimedean spiral slit fabricated on atomically flat aluminum epitaxial film, which allows for precise tuning of plasmonic resonances and subsequent transfer of two-dimensional materials on top of the spiral slit. The nonlinear optical measurements show a giant SHG circular dichroism. Furthermore, we have achieved an enhanced chiral SHG conversion efficiency (about an order of magnitude greater than the bare aluminum lens) from monolayer tungsten disulfide (WS2)/aluminum metalens, which is designed at the C-exciton resonance of WS2. Since the C-exciton is not a valley exciton, the enhanced chiral SHG in this hybrid system originates from the plasmonic vortex field-enhanced SHG under the optical spin-orbit interaction.

Original languageEnglish
Pages (from-to)2857-2864
Number of pages8
JournalNano letters
Volume20
Issue number4
DOIs
StatePublished - 8 Apr 2020

Keywords

  • aluminum epitaxial film
  • chiral nonlinearity
  • monolayer tungsten disulfide
  • optical spin-orbit interaction
  • second-harmonic generation
  • Surface plasmonic vortex metalens

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