Millivolt modulation of a plasmonic metasurface via ionic conductance

We report here and experimentally demonstrate an actively controlled gate-tunable plasmonic metasurface operating in the visible region of the electromagnetic spectrum, where – strikingly – the operating voltages for reflectance modulation are much less than 1V. The electrically tunable metasurface consists of inverse dolmen structures (iDolmen) patterned on silver and chromium on a quartz substrate and subsequently covered with a 5 nm thin layer of Al2O3 followed by a 110 nm indium tin oxide (ITO) layer, which acts as a transparent electrode. Our designed structures show up to 78% change in reflection upon applying small voltages (<1V). We explain this behaviour via ion conductance of silver through Al2O3 and ITO, leading to active