Optically Active Metasurface with Non-Chiral Plasmonic
Nanoantennas
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Abstract
We design, fabricate, and experimentally
demonstrate an optically
active metasurface of 位/50 thickness that rotates linearly polarized
light by 45掳 over a broadband wavelength range in the near IR
region. The rotation is achieved through the use of a planar array
of plasmonic nanoantennas, which generates a fixed phase-shift between
the left circular polarized and right circular polarized components
of the incident light. Our approach is built on a new supercell metasurface
design methodology: by judiciously designing the location and orientation
of individual antennas in the structural supercells, we achieve <i>an effective chiral metasurface</i> through <i>a collective
operation of nonchiral antennas</i>. This approach simplifies
the overall structure when compared to designs with chiral antennas
and also enables a chiral effect which <i>quantitatively</i> depends solely on the supercell geometry. This allows for greater
tolerance against fabrication and temperature effects