Sensitivities of large-aperture plasmonic metasurface flat lenses in the long-wave infrared

Plasmonic metasurface lenses based on polarization conversion are inherently limited in efficiency, and as a result, they have been given sparse attention in favor of higher-performing dielectric variants. However, recent proposals for expanding the design beyond a single interface offer hope for efficient plasmonic structures. Before developing these multi-layer structures, we wish to better understand dependencies of 2D plasmonic designs. Here we demonstrate the spectral, polarization and geometrical sensitivities of nine large-scale variants of the original V-antenna lens design at λ 0 = 8μm. We show that the spectral response oscillates rapidly within a span as small as λ 0 /320, and that strong focusing can occur at both the designed polarization state, and its orthogonal state–and with differing focal distances. Additionally, we determine that the lens performance is only weakly tied to the size of the discretization, offering only marginal improvement as the discretization approaches a continuum.