Enhanced terahertz transmission through a periodic array of tapered   rectangular apertures
  We numerically analyse extraordinary terahertz transmission properties of an array of rectangular shaped apertures perforated periodically on a thin metal film. The apertures are tapered at different angles to achieve higher field concentration at the tapered end. The periodic sub-wavelength scale apertures ensure plasmonic behaviour giving rise to the enhanced transmission of a specific frequency mode decided by the periodicity. We compare results of transmission with the rectangular shaped apertures of same parameters and observe a significant increase in the transmission for the tapered case. We have compared results of our numerical simulations with theory and have found them consistent. 
Koijam Monika Devi, Amarendra K. Sarma and Gagan Kumar
physics.optics