Plasmonic Control of Optical Properties of Metal Films: Enhancement of Extraordinary Optical Transmission and Polarization Control of Diffraction from Sub-wavelength Aperture Arrays

Nano-hole arrays in metal films have been the topic of intense research over the past decade. They serve as an aid to channel the surface plasmons on the metal surface to achieve very specific optical properties in the resulting structure. These properties have been found to be very useful in spectroscopy and sensor applications. Sub-wavelength aperture array structures are presented to enhance the extraordinary optical transmission from nano-hole arrays by reflecting the surface plasmons scattering off the edge the array and redirecting back towards the array, resulting in enhanced transmission. The polarization sensitive properties of surface plasmons are used to control diffraction from a nano-hole array. Quasiperiodic strutures with rotationally symmetric diffraction patterns are fabricated and the diffraction from these structures are controlled using polarization of incident light. These structures have potential applications in spectroscopic applications.