SPOOF SURFACE PLASMONS AND CIRCUIT MODEL FOR EXTRAORDINARY TRANSMISSION THROUGH ASYMMETRIC PERIODIC ARRAY OF SUBWAVELENGTH STEPPED SLITS

Abstract

In this paper conversion from spatial propagating waves to surface plasmon polaritons (SPPs) has been studied. The conversion from spatial propagating waves to surface plasmon polaritons (SPPs) has been well studied, and shown to be very efficient by using gradient-index metasurfaces. However, feeding energies into and extracting signals from functional plasmonic devices or circuits through transmission lines require the efficient conversion between SPPs and guided waves. In the first part a smooth conversion of CPW electromagnetic waves into spoof SPPs with good efficiency has been shown. For this purpose a three region structure has been shown. It has gradient corrugated slits to match momentum of CPW waves and SPP waves as well as a flaring ground to match impedance of CPW waves and SPP waves. The results obtained on CST software shows that the given structure provide good transition between CPW and SPP waves with very high efficiency. In the second part of this paper, shows the probable ways of improving the efficiency of the conversion from spatial propagating waves to surface plasmon polaritons (SPPs). In order to do so the unit cell structure is changed such that it has metallic slits which are capacitive coupled and are separated by dielectric medium. To study this EOT through periodically corrugated holes or slits of size smaller than wavelength in metal film, we design two circuit model 1st we design a cascade model and 2nd we design a stub model for the condition when cascade model is inaccurate.