Controllable directive radiation of a magnetic dipole above planar metal surface

TL;DR

This paper demonstrates controllable unidirectional radiation from a magnetic dipole above a metal surface, achieved by adjusting the dipole-surface distance, revealing a novel mechanism for light emission control distinct from nanoantenna approaches.

Contribution

It introduces a new method for directing magnetic dipole radiation using interference effects near a metal surface, expanding light emission engineering capabilities.

Findings

Radiation direction can be tuned by changing dipole-surface distance.

Unidirectional radiation is unique to magnetic dipoles on metal surfaces.

The physics is explained by interference of orthogonal dipole components with phase lag.

Abstract

We report unidirectional radiation of a magnetic dipole above planar metal surface, the radiation direction can be manipulated via changing the distance between the dipole and the surface. This phenomenon is unique for the combination of magnetic dipole and metal surface and does not happen for linear polarized dipole on metal surface or magnetic dipole on dielectric surface. The underlining physics is analytically disclosed by the interference of two orthogonally-oriented dipole component with \pi/2 phase lag. A substantially different mechanism of introducing the vectorial nature of the dipole itself to control light emission distinguishes the present scheme from nanoantenna and provides a new degree of freedom in light emission engineering.