Electrically tunable optical metasurface color filters based on sub-skin-depth metallic structures using electroplating

Abstract

Metamaterials and metasurfaces are materials where sub-wavelength scale motifs are 3 or 2 dimensionally arrayed and are highly demanded due to their unprecedented properties in optics. Tunability of metamaterials and metasurfaces are highly researched topics because those researches suffered from their low controllability after fabrication. In this thesis, we suggest new mechanism to give tunability in metamaterials and metasurfaces. Skin depth means how long electromagnetic waves can penetrate in lossy materials, metals as examples, and is denoted by the thickness where intensity of electromagnetic waves decrease to 1/e of incident waves. Optical properties of optical device consisting metal thin films thinner than skin depth can significantly change by modulating metal thickness. We achieved metal thickness modulation with electrochemical mechanism, electrodeposition, that metal is deposited by voltage appliance in electrolytes. As a result, we realized color filter by voltage appliance,