  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.
