Chapter 9 - Resonant optical antennas and single emitters

Abstract

The chapter discusses resonant optical antennas and single emitters. The efficiency of interconversion between propagating electromagnetic fields and local fields strongly depends on the geometry and the material properties of the respective antenna. The field enhancement in an antenna feed gap and its dependence on the antenna length is analyzed in the chapter. To create a resonant circuit, an alternative approach is to keep the frequency fixed and tune the antenna length. The advantage of the bowtie geometry is that the field is concentrated in single maximum because the charges at the long sides of triangles are allowed to spread over a much larger spatial region. If a single emitter is brought in close proximity of a metal nanostructure, the optical properties of the molecule and the optical l properties of the metal nanostructure become important for the behavior of the total system. The properties of single-dipole emitters near metal nanostructures are analyzed in the chapter. The resonant excitations play an important role for the behavior of resonant optical antennas made from noble metals.