Abstract
The ability to design the electromagnetic properties of materials to achieve any given wave scattering effect is key to many technologies, from communications to cloaking and biological imaging. Currently, common design methods either neglect degrees of freedom or are difficult to interpret. Here, we derive a simple and efficient method for designing wave–shaping materials composed of dipole scatterers, taking into account multiple scattering effects and both magnetic and electric polarizabilities. As an application of our theory, we design aperiodic metasurfaces that re-structure the radiation from a dipole emitter: (i) modifying of the near-field to provide a 4-fold enhancement in power emission; (ii) re-shaping the far-field radiation pattern to exhibit chosen directivity; and (iii) the design of a discrete Luneburg–like lens. Additionally, we develop a clear physical interpretation of the optimised structure, by extracting eigen-polarizabilities of the system, finding that a large eigen-polarizability corresponds to a large collective response of the scatterers.
Highlights
The ability to design the electromagnetic properties of materials to achieve any given wave scattering effect is key to many technologies, from communications to cloaking and biological imaging
Some of the earliest examples of metasurfaces are frequency selective surfaces[13,14]. These are a class of periodically structured two-dimensional metal-dielectric structures designed to have specific reflection and transmission properties that depend upon the frequency of the incident wave
In this work, we have derived a method of designing metamaterials comprised of small scatterers. This has been applied to design aperiodic planar structures that have a predetermined effect on both the near- and the far-field of a dipole emitter
Summary
The ability to design the electromagnetic properties of materials to achieve any given wave scattering effect is key to many technologies, from communications to cloaking and biological imaging. Integrating the Green function (6) against the source total electric field, the PLDoS is given by[53] currents (3), it can be shown that the solution to Maxwell’s equations (1) and (2) can be written in terms of the outgoing wave solution and its curl
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