Magnetic-Dipolar-Mode Oscillations for Near- And Far-Field Manipulation of Microwave Radiation

Abstract

Abstract-There has been a surge of interest in the subwavelength confinement effects of the electromagnetic fields. Based on these effects, one can obtain new behaviors of the near-and far-field radiation.It is well known that in optics, the subwavelength confinement can be obtained due to surface-plasmon (or electrostatic) oscillations in metal structures. This paper is a review of recent studies on the subwavelength confinement in microwaves due to magnetic-dipolar-mode (MDM) [or magnetostatic (MS)] oscillations in small ferrite samples. MDM oscillations in a mesoscopic ferritedisk particle are quantized oscillations, which are characterized by energy eigenstates. The field structures are distinguished by powerflow vortices and non-zero helicity. Also in vacuum, the near fields originated from MDM particles are designated by topologically distinctive power-flow vortices, non-zero helicity, and a torsion degree of freedom.To differentiate such field structures from regular electromagnetic (EM) field structures, we term them as magnetoelectric (ME) fields. In a pattern of the microwave field scattered by a MDM ferrite disk and MDM-disk arrays, one can observe rotating topological-phase dislocations. This opens a perspective for creation of engineered electromagnetic fields with unique symmetry properties. In the near-field applications, we propose novel microwave sensors for material characterization, biology, and nanotechnology. Strong energy concentration and unique topological structures of the near fields originated from the MDM resonators allow effective measuring chiral properties of materials in microwaves. Generating

Topological properties of microwave magnetoelectric fields

“…Generating far-field orbital angular momenta from near-field microwave chirality of MDM structures can be a subject of great interest. Realization of such vortex generators opens the perspective for far-field microwave systems with topological-phase modulation [46].…”

Quantization of magnetoelectric fields

“…From literature, one can see that for the MDM spectral problem formulated exceptionally for the MS-potential wave function ( , ) rt  , no use of the alternative electric fields is presumed [20 -22, 37 -39]. Following a formal analysis [40,41] it can be also shown that for MDM oscillations, the Faraday equation is incompatible with Eqs. (1) and (2 [42] it was merely stated that in a case of the MDM spectral problem, an electric field is completely absent and thus 0 E    .…”