Investigation of a cross-slot nanoantenna and extraordinary transmission

Using finite integration technique, the authors investigate the properties of a cross-nanoslot formed in silver film, from the perspective of a plasmonic antenna, and examine the transmission of light through its periodic array. The cross-slot nanoantenna (CSNA) can enhance the intensity of near field by orders of magnitude, independent of polarisation of incident light, and emit omnidirectionally when excited by two identical sources of orthogonal polarisation operating in phase quadrature. An array of CSNA exhibit extraordinary transmission, which can be enhanced further by placing complementary cross-nanostripe array at an optimum position. To the authors' best knowledge, this is the first exploration of a cross-nanoslot as an antenna.