Wedge nanostructures for plasmonic nanofocusing

We report numerical and experimental results on the optical response of transparent metal coated wedges arrays for plasmonic nanofocusing. Light normally impinging from the dielectric side is coupled to Surface Plasmon Polaritons (SPPs) at the oblique metal-air interfaces. A dielectric phase shifter has been implemented in the structure in order to allow constructive interference of SPPs at the wedge apex. Finite Elements simulations were used to design the system. Focused Ion Beam (FIB) milling, chemical etching and replica molding were used for the fabrication. NSOM and Raman measurements demonstrate that plasmonic nanofocusing actually takes place in the structure.