THz near-field Faraday imaging in hybrid metamaterials

Opt Express. 2012 May 7;20(10):11277-87. doi: 10.1364/OE.20.011277.


We report on direct measurements of the magnetic near-field of metamaterial split ring resonators at terahertz frequencies using a magnetic field sensitive material. Specifically, planar split ring resonators are fabricated on a single magneto-optically active terbium gallium garnet crystal. Normally incident terahertz radiation couples to the resonator inducing a magnetic dipole oscillating perpendicular to the crystal surface. Faraday rotation of the polarisation of a near-infrared probe beam directly measures the magnetic near-field with 100 femtosecond temporal resolution and (λ/200) spatial resolution. Numerical simulations suggest that the magnetic field can be enhanced in the plane of the resonator by as much as a factor of 200 compared to the incident field strength. Our results provide a route towards hybrid devices for dynamic magneto-active control of light such as isolators, and highlight the utility of split ring resonators as compact probes of magnetic phenomena in condensed matter.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Computer Simulation
  • Equipment Design
  • Gallium / chemistry
  • Light
  • Magnetic Fields
  • Magnetics
  • Physics / methods
  • Refractometry / methods
  • Scattering, Radiation
  • Signal Processing, Computer-Assisted
  • Spectroscopy, Near-Infrared / methods
  • Terahertz Radiation*
  • Terbium / chemistry
  • Time Factors


  • Terbium
  • Gallium