Magnetic dipole and electric dipole resonances in TiO2 microspheres at terahertz frequencies

Oleg Mitrofanov (1) , Filip Domenic (2) , P. Kuzel (3) , John Reno (1) , Igal Brener (4) , U-Chan Chung (5) , Catherine Elissalde (5) , Mario Maglione (5) , Patrick Mounaix (6)

1 Center for Integrated Nanotechnologies
2 CAS - Czech Academy of Sciences [Prague]
3 Institute of Physics
4 SNL - Sandia National Laboratories [Albuquerque]
5 ICMCB - Institut de Chimie de la Matière Condensée de Bordeaux
6 IMS - Laboratoire de l'intégration, du matériau au système

n a non-magnetic dielectric sphere of high-permittivity ( <20), effective magnetic response occurs as a result of the 1st Mie mode, known as the magnetic dipole resonance. This resonance produces a similar effect as split ring resonators, making it possible to use dielectric spheres as metamaterial components. In the terahertz (THz) part of the spectrum, where dielectrics with  ~100 can be found, all-dielectric metamaterials can potentially reduce absorption and provide isotropic and polarization-independent properties. In this contribution, we discuss TiO2 micro-spheres, ~1/10 of the wavelength in diameter. Such spheres are expected to support the magnetic and electric dipole resonances. To detect these resonances in a single TiO2 microsphere we use THz near-field microscopy with the sub-wavelength size aperture probe. This method allows detection of Mie resonances in single sub-wavelength spheres. Fano-type line-shape is observed in the near-field amplitude and phase spectra. The narrow line-width of the magnetic resonance and the subwavelength size of the TiO2 microspheres make them excellent candidates for realizing low-loss THz metamaterials. © (2015) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.

Mots clés: Terahertz; Metamaterial; metamaterials; dielectric resonator; near-field imaging; Mie mode; TiO2 micro-sphere; Fano lineshape; THz spectroscopy

Domaines: Matière Condensée [cond-mat]; Electromagnétisme

Oleg Mitrofanov, Filip Domenic, P. Kuzel, John Reno, Igal Brener, et al.. Magnetic dipole and electric dipole resonances in TiO2 microspheres at terahertz frequencies. Quantum Sensing and Nanophotonic Devices XII,, Feb 2015, San Francisco, United States. ⟨10.1117/12.2079734⟩. ⟨hal-01263842⟩