  Bidirectional nanoantennas are of key relevance for advanced functionalities
to be implemented at the nanoscale, and in particular for color routing in an
ultracompact flat-optics configuration. Here we demonstrate a novel approach
avoiding complex collective geometries and/or restrictive morphological
parameters, based on cross-polarized detuned plasmonic nanoantennas in a
uniaxial (quasi-1D) bimetallic configuration. The nanofabrication of such a
flat-optics system is controlled over a large-area (cm^2) by a novel
self-organized technique exploiting ion-induced nanoscale wrinkling instability
on glass templates to engineer tilted bimetallic nanostrip dimers. These
nanoantennas feature broadband color routing with superior light scattering
directivity figures, which are well described by numerical simulations and turn
out to be competitive with the response of lithographic nanoantennas. These
results demonstrate that our large-area self-organized metasurfaces can be
implemented in real world applications of flat optics color routing from
telecom photonics to optical nanosensing.
