Large chiro-optical effect in stacked chiral metamaterials

Plasmonic nanostructures in chiral geometries are suitable candidates for various device applications pertaining to optical polarization. These devices can show large chiro-optical effects, implying a strongly differential response to right and left circularly polarized light. In general, three-dimensional plasmonic structures show larger optical activity, but are typically not suitable for wafer-scale fabrication. As an alternate strategy, we have considered the optical response of stacked planar chiral geometries, which were found to exhibit very large chiro-optical response. Further, the plasmonic chirality of such stacked metamaterials can be tuned in the visible, by simply varying the thickness of the stack. This novel design of layered achiral metamaterials will be easier to fabricate than standard three dimensional geometries, and is suitable for various photonic device applications requiring polarization control.