title: Near-field probing of Mie resonances in single TiO2 microspheres at terahertz frequencies.
abstract: 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.
authors.forename: Oleg
authors.initials: O
authors.lastname: Mitrofanov
authors.forename: Filip
authors.initials: F
authors.lastname: Dominec
authors.forename: Petr
authors.initials: P
authors.lastname: Kužel
authors.forename: John L
authors.initials: JL
authors.lastname: Reno
authors.forename: Igal
authors.initials: I
authors.lastname: Brener
authors.forename: U-Chan
authors.initials: UC
authors.lastname: Chung
authors.forename: Cathy
authors.initials: C
authors.lastname: Elissalde
authors.forename: Mario
authors.initials: M
authors.lastname: Maglione
authors.forename: Patrick
authors.initials: P
authors.lastname: Mounaix
mesh_terms: D003198:Computer Simulation; D004867:Equipment Design; D008863:Microspheres; D055053:Terahertz Radiation; D055068:Terahertz Spectroscopy / Q000295:instrumentation*; D014025:Titanium / Q000737:chemistry*
chemical_list: C009495:titanium dioxide; D014025:Titanium