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Polarity of the Fano Resonance in the Near‐Field Magnetic‐Dipole Response of a Dielectric Particle Near a Conductive Surface
Author(s) -
Khromova Irina,
Sayanskiy Andrey,
Uryutin Andrey,
Evlyukhin Andrey B.
Publication year - 2018
Publication title -
laser and photonics reviews
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.778
H-Index - 116
eISSN - 1863-8899
pISSN - 1863-8880
DOI - 10.1002/lpor.201800037
Subject(s) - dipole , fano resonance , physics , resonance (particle physics) , electric field , magnetic dipole , condensed matter physics , dielectric , near and far field , magnetic field , polarity (international relations) , optics , atomic physics , plasmon , chemistry , optoelectronics , biochemistry , quantum mechanics , cell
Abstract Fano resonances are observed in the near‐field electric‐field spectra of dielectric particles sustaining magnetic dipole resonances and located in the vicinity of a conductive surface (reflector). The polarity of these Fano resonances is defined by the relative positions of the resonant particle, the observation points, and the reflector. This paper studies two cases corresponding to common near‐field measurement techniques, where the electric field is detected by aperture‐based probes and scattering probes. In the first case, as the particle moves away from the reflector, the polarity of the observed Fano resonance reverses every quarter‐of‐a‐wavelength of the particle's magnetic resonance. In the second case, in addition to the periodic change of polarity, a phase shift of π is detected between the fields detected at the opposite sides of the resonant particle. This work proves, theoretically, that the observed Fano resonance polarities arise due to the interference between the external electric‐field standing wave and the resonant fields generated by the particle's magnetic dipole moment. The findings are supported by a recent terahertz experiment and the gigahertz experiment presented in this paper.