Frontiers in Physics (Mar 2023)

Enhanced terahertz third-harmonic generation by bound states in the continuum in graphene grating-like metamaterial

  • Baoku Wang,
  • Jing Liu,
  • Jinhui Cui,
  • Jialin Liu,
  • Fengjun Tian,
  • Weimin Sun,
  • Li Li,
  • Li Li

DOI
https://doi.org/10.3389/fphy.2023.1135211
Journal volume & issue
Vol. 11

Abstract

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Non-linear metamaterials hold great promise for enhanced terahertz harmonic generation. Here, we numerically investigate enhanced terahertz third-harmonic generation (THG) by exploiting the symmetry-protected bound states in the continuum (BICs) in graphene grating-like metamaterial. By symmetry breaking of metamaterials, BICs transform into quasi-BICs. The high Q-factor and strong localized field enhancement is achieved at quasi-BICs, leading to a boosted THG process with low incident intensity of fundamental frequency. The THG conversion efficiency reaches 3.1% at an incident intensity of 100 kW/cm2. The remarkably enhanced non-linear optical process in the proposed non-linear metamaterial constitutes an outstanding platform for on-chip terahertz non-linear conversion applications.

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