  A new configuration for metasurface construction is presented to achieve
multi-functional capabilities including perfect absorption, bio/chem sensing,
and surface-mode lasing. The reciprocal plasmonic metasurfaces discussed here
are composed of two plasmonic surfaces of reciprocal geometries separated by a
dielectric spacer. Compared to conventional metasurfaces this simple geometry
exhibits an enhanced optical performance. The discussed reciprocal metasurface
design further enables effective structural optimization and allows for a
simple and scalable fabrication. The physical principle and potential
applications of the reciprocal plasmonic metasurfaces are demonstrated using
numerical and analytical approaches.
