Metasurfaces based dual wavelength diffractive lenses.

We demonstrate experimentally and by simulations a method for using thin nanostructured plasmonic metasurfaces to design diffractive Fresnel zone plate lenses that focus pairs of wavelengths to a single focal point. The metasurfaces are made of tightly packed cross and rod shaped optical nanoantennas with strong polarization and wavelength selectivity. This selectivity allows multiplexing two different lenses with low spectral crosstalk on the same substrate and to address any superposition of the two colors at the focus of the lenses by controlling the polarization of light. This concept can open the door to use ultrathin diffractive lenses in fluorescence microscopy and in stimulated emission depletion microscopy.