MAGNETIC-DIPOLAR-MODE OSCILLATIONS FOR NEAR- AND FAR-FIELD MANIPULATION OF MICROWAVE RADIATION

Abstract

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