Giant magneto-electric field separation via near-field interference on anapole-like states

TL;DR

This paper demonstrates a novel dielectric tube structure that achieves record-high spatial separation of electric and magnetic fields using near-field interference on anapole-like states, surpassing free space limitations.

Contribution

It introduces a new design of coupled dielectric tubes that enables tunable, high-quality electric-magnetic field separation through near-field interference, both theoretically and experimentally.

Findings

Record high spatial separation of electric and magnetic fields achieved.

Experimental validation of near-field interference on anapole-like states.

Enhanced magnetic field alongside electric-magnetic separation.

Abstract

Quality of spatial separation between electric and magnetic fields in an electromagnetic wave is fundamentally constrained by nonlocal nature of Maxwell equations. While electric and magnetic energy densities in a wave, propagating in vacuum, are equal at each point in space, carefully designed photonic structures can enable surpassing this limit. Here, a set of high index dielectric tubes was for the first time proposed and theoretically and experimentally demonstrated to deliver a record high spatial separation, overcoming the free space scenario by more than three orders of magnitude with simultaneous enhancement of the magnetic field. Separation effect in the proposed structure is enabled by the near-field interference on anapole-like states, designed by tuning geometrical parameters of coupled dielectric tubes. The void layout of the structure enables the direct observation of the effect with near-field probes and could be further employed for relevant applications. Novel devices, providing tunable high quality separation between electric and magnetic fields, are extremely important for metrology, spectroscopy, spintronics, and opto-electronic applications.