Ultrasensitive and Broadband Optical Toroidal Modes in all-Dielectric Nanostructures

Hui Hsin Hsiao*, Ai Yin Liu

*此作品的通信作者

研究成果: 雜誌貢獻期刊論文同行評審

摘要

Dynamic toroidal dipole (TD) with its peculiar characteristic of broken space-inversion and time-reversal symmetries plays an important role in the fundamental physics of light–matter interaction. Here, TD metamaterials comprised of amorphous silicon nanopillar arrays embedded in spin-on-glass layer are experimentally demonstrated. Upon normal incidence of plane wave, the transverse toroidal moment and the associated anapole-like state are excited in optical regime. The strong TD response stems from a complete head-to-tail configuration of the magnetic dipole moments within each individual nanopillar. Both the experimental and simulation results show that such TD mode sustains a large structural tolerance and can be spectrally tuned by elongating the cylindrical axis perpendicular to the light polarization, corresponding to a cross-sectional variation from circular to elliptical shapes. The excited TD mode is found to exhibit ultrahigh refractive index sensitivity compared to other multipoles, resulting in a sensitivity of 459 nm (470 nm) per external refractive index change in the experiment (calculation). This approach provides a simple and straightforward path in realizing toroidal metamaterials and establishes a new flat-optics platform for realizing active metadevices, sensors, and nonlinear nanophotonics.

原文英語
文章編號2100404
期刊Laser and Photonics Reviews
16
發行號3
DOIs
出版狀態已發佈 - 2022 3月

ASJC Scopus subject areas

  • 電子、光磁材料
  • 原子與分子物理與光學
  • 凝聚態物理學

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