High efficiency plasmonic probe design for parallel near-field optics applications

Abstract

We study a high efficiency plasmonic near-field probe that integrates a spiral plasmonic lens and a sharp conical tip under circular polarized illumination. To achieve high field enhancement, two layers of spiral plasmonic lens and a composite tip design are adopted. The plasmonic probe exhibits optical spin dependence due to the use of spiral plasmonic lens. Under 633 nm wavelength excitation, an electric field enhancement factor of 366 and circular polarization extinction ratio of 81 can be achieved. Such a spin dependence enables the hot spot at the tip apex to be switched on and off by modulating the polarization handedness. The probe can be made in an array format that is suitable for large area parallel near-field optics applications such as lithography and microscopy.