Designing disordered multi-functional metamaterials using the discrete dipole approximation

Abstract

The ability to design passive structures that perform different operations on different electromagnetic fields is key to many technologies, from beam-steering to optical computing. While many techniques have been developed to optimise structures to achieve specific functionality through inverse design, designing multi-function materials remains challenging. We present a semi-analytic method, based on the discrete dipole approximation, to design multi-functional metamaterials. To demonstrate the generality of our method, we present two key examples. Firstly, we work at optical wavelengths to design a disordered 2D arrangement of silicon spheres that beams light into different directions depending on the source polarisation. Secondly, we design a 3D device that works at microwave wavelengths and sorts plane waves by their angle of incidence. In this case, the scatterers are more complicated meta-atoms, with a strong dipole resonance at microwave frequencies.