摘要
Controlling the phase of an electromagnetic field using plasmonic nanostructures provides a versatile way to manipulate light at the nanoscale.Broadband phase modulation has been demonstrated using inhomogeneous metasurfaces with different geometries;however,for many applications such as filtering,hyperspectral imaging and color holography,narrowband frequency selectivity is a key functionality.In this work,we demonstrate,both theoretically and experimentally,a narrowband metasurface that relies on Fano resonances to control the propagation of light.By geometrically tuning the sub-radiant modes with respect to a fixed super-radiant resonance,we can create a phase modulation along the surface within a narrow spectral range.The resulting anomalous reflection measured for such a Fano-resonant metasurface exhibits a 100 nm bandwidth and a color routing efficiency of up to 81%at a central wavelength ofλ=750 nm.The design flexibility provided by this Fano-assisted metasurface for colorselective light manipulation is further illustrated by demonstrating a highly directional color-routing effect between two channels,atλ=532 and 660 nm,without any crosstalk.
基金
supported by the Swiss National Science Foundation(grants 200020_153662 and 200021_162453).
