Splitting of magnetic dipole modes in anisotropic TiO2 micro‐spheres. Issue 4 (27th June 2016)

• Record Type: Journal Article
• Authors: Khromova, Irina; Kužel, Petr; Brener, Igal; Reno, John L.; Chung Seu, U‐Chan; Elissalde, Catherine; Maglione, Mario; Mounaix, Patrick; Mitrofanov, Oleg
• Is Part Of: Laser & photonics reviews. Volume 10:Issue 4(2016:Jul.)
• Page Start: 681
• Page End: 687
• Publication Date: 2016-06-27
• Subjects: Terahertz spectroscopy -- Mie scattering -- dielectric metamaterials -- magnetic dipole; Lasers -- Periodicals; Photonics -- Periodicals; Lasers -- Périodiques; Photonique -- Périodiques; 621.36
• DOI: 10.1002/lpor.201600084
• Languages: English
• ISSNs: 1863-8880

Abstract

Abstract : Strong dielectric anisotropy at terahertz (THz) frequencies splits the Mie magnetic dipole mode in monocrystalline titanium dioxide (TiO2 ) micro‐spheres. The splitting is experimentally confirmed using near‐field THz time‐domain spectroscopy. The resonances correspond to orthogonal magnetic dipole modes with narrow linewidths of only tens of gigahertz. The anisotropy of TiO2 can be exploited in the emerging THz all‐dielectric metamaterial technology. Abstract: Monocrystalline titanium dioxide (TiO2 ) micro‐spheres support two orthogonal magnetic dipole modes at terahertz (THz) frequencies due to strong dielectric anisotropy. For the first time, we experimentally detected the splitting of the first Mie mode in spheres of radii 10 − 20 μ m through near‐field time‐domain THz spectroscopy. By fitting the Fano lineshape model to the experimentally obtained spectra of the electric field detected by the sub‐wavelength aperture probe, we found that the magnetic dipole resonances in TiO2 spheres have narrow linewidths of only tens of gigahertz. Anisotropic TiO2 micro‐resonators can be used to enhance the interplay of magnetic and electric dipole resonances in the emerging THz all‐dielectric metamaterial technology.