Optimization of light-surface plasmon coupling by periodicity regulation for a pyramidal probe

It has been reported that periodic corrugations can enhance light intensity transmitted through a sub-wavelength size aperture by the light-surface plasmon coupling. In this report, we considered the light transmission through a nano-aperture formed on a metal-coated pyramidal probe which is surrounded by specially designed periodic grooves. 'Elliptic-type' periodic grooves have been fabricated with a focused ion beam by varying the periodicity. This type of groove was designed so that the grooves form concentric arcs centered at the pyramid apex on each triangular sidewall of the pyramid. This type of groove is thought to be ideal for the coupling of light-to-surface plasmon on a pyramidal probe. Examination on the light transmission enhancement due to the surface plasmon has been performed through fabrication, optical measurement, and a simulation analysis based on FDTD method. The details of fabrication procedure, experimental results with analysis will be comprehensively discussed.