Controlling the polarization orientation of highly confined and enhanced surface plasmon polaritons

Abstract

We demonstrate a schematic method to tune and control the polarization orientation of surface plasmon polaritons highly confined and enhanced to nanoscale spots. Two types of nanostructures are used and illuminated with a specially designed excitation source which is created by directing a radially polarized beam onto a half-blocked linear polarizer. The overall polarization orientation is defined and calculated. It is demonstrated that the azimuthal angle of the overall polarization orientation can be arbitrarily tuned by rotating the one lobe linearly polarized beam azimuthally and the polar angle of the overall polarization orientation can be adjusted by using different thick circular disks with a diameter less than the wavelength of the surface plasmon polaritons. The highly confined and enhanced light field with tunable polarization orientation may make many applications more attractive and applicable, especially for polarization-sensitive sensing techniques and other nanoscale devices.