Controlling the Colour of Metals: Intaglio and Bas-Relief Metamaterials

TL;DR

This paper introduces a novel method for controlling metal colour through sub-wavelength metamaterial patterns, enabling versatile and scalable aesthetic and functional applications without chemical or coating modifications.

Contribution

It presents a new approach to structural colouring of metals using intaglio and bas-relief metamaterials, avoiding traditional surface treatments.

Findings

A broad range of colours can be achieved by tuning structural parameters.

The method is scalable and versatile for aesthetic and functional uses.

Applicable to visible spectrum and other electromagnetic domains.

Abstract

The fabrication of indented ('intaglio') or raised ('bas-relief') sub-wavelength metamaterial patterns on a metal surface provides a mechanism for changing and controlling the colour of the metal without employing any form of chemical surface modification, thin-film coating or diffraction effects. We show that a broad range of colours can be achieved by varying the structural parameters of metamaterial designs to tune absorption resonances. This novel approach to the 'structural colouring' of pure metals offers great versatility and scalability for both aesthetic (e.g. jewellery design) and functional (e.g. sensors, optical modulators) applications. We focus here on visible colour but the concept can equally be applied to the engineering of metallic spectral response in other electromagnetic domains.