Hybrid Photonic–Plasmonic Metastructures

This chapter considers hybrid metastructures operating in waveguide configuration. This configuration can unlock unprecedented functionalities when the interplay between quantum emitters and plasmonic nanostructures is efficiently exploited. The chapter begins with an introduction of the Purcell effect responsible for the emission enhancement of fluorescent subentities when located in nanocavities. Introductory paragraphs also explain the basic mechanisms of the plasmon–exciton exchange. The design of a hybrid system follows including plasmonic nanotapers (NTs) with quantum dots (QDs) positioned in proximity to their apices. The various phases of the fabrication procedure of the designed metastructure, involving a mixed top-down and bottom-up nanofabrication approach, are accurately illustrated. A fluorescent spectroscopy characterization of the prototype evidences a sensitive Purcell enhancement of the emission of the quantum dots located in proximity of the NTs. Finally, a numerical study of this hybrid system is reported that demonstrates how the light enhancement can be controlled to efficiently route and modulate high-frequency optical signals in a photonic–plasmonic transistor effect.