Nanoscale Electrical Excitation of Surface Plasmon Polaritons with a Nanoantenna Tunneling Junction
Delphine Pommier, Zélie Hufschmitt, Cheng Zhang, Yunhe Lai, Gérald Dujardin, Eric Le Moal, Christophe Sauvan, Jean‐Jacques Greffet, Jianfang Wang, Élizabeth Boer-Duchemin
Abstract
Quantum tunneling-driven optical nanoantennas are key components for the development of integrated plasmonic nanodevices. In this work, we use the tunneling junction between a nanoantenna and a thin gold film to electrically excite propagating surface plasmons on the nanoscale. The nanoantenna is a chemically synthesized gold nanocube (∼50 nm side length) that is separated from a thin (50 nm) gold film by an insulating molecular layer (1,8-octanedithiols, ∼1 nm thick). A novel method for completing the electrical circuit between the nanoantenna and the gold film using an atomic force microscope (AFM) is developed. Based on the results of numerical modeling, the nanoantenna modes exciting the propagating surface plasmon polaritons are identified as hybridized gap and antenna modes. Our results demonstrate the ability to interrogate individual tunneling-driven nanoantennas, a crucial step toward the development of electrical nanosources of surface plasmon polaritons and light.