Near-field probing of Mie resonances in single TiO2 microspheres at terahertz frequencies

Oleg Mitrofanov (1, 2) , Filip Dominec (3) , Petr Kužel (3) , John L. Reno (2, 4) , Igal Brener (2, 4) , U-Chan Chung (5) , Catherine Elissalde (5) , Mario Maglione (5) , Patrick Mounaix (6)

1 DEEE - Department of Electronic and Electrical Engineering
2 CIN - Center for Integrated Nanotechnologies
3 Institute of Physics [Prague]
4 SNL - Sandia National Laboratories [Albuquerque]
5 ICMCB - Institut de Chimie de la Matière Condensée de Bordeaux
6 LOMA - Laboratoire Ondes et Matière d'Aquitaine

We show experimentally that poly-crystalline TiO2 spheres, 20-30 μm in diameter, exhibit a magnetic dipole Mie resonance in the terahertz (THz) frequency band (1.0-1.6 THz) with a narrow line-width (<40 GHz). We detect and investigate the magnetic dipole and electric dipole resonances in single high-permittivity TiO2 microspheres, using a near-field probe with a sub-wavelength (~λ/50) size aperture and THz time-domain spectroscopy technique. The Mie resonance signatures are observed in the electric field amplitude and phase spectra, as well as in the electric field distribution near the microspheres. The narrow line-width and the sub-wavelength size (λ/10) make the TiO2 microspheres excellent candidates for realizing low-loss THz metamaterials.

Mots clés: Resonators; Spectroscopy; Terahertz; Terahertz imaging.; Terahertz imaging; Metamaterials; Near-field microscopy

Domaines: Matériaux

Oleg Mitrofanov, Filip Dominec, Petr Kužel, John L. Reno, Igal Brener, et al.. Near-field probing of Mie resonances in single TiO2 microspheres at terahertz frequencies. Optics Express, 2014, 22 (19), pp.23034-23042. ⟨10.1364/OE.22.023034⟩. ⟨hal-01064594⟩