Commentary: Multiple surface-plasmon-polariton waves at a single bi-material interface
Electromagnetic surface waves have been a subject of investigation since the beginning of the 20th century when Zenneck proposed that radio waves might propagate as surface waves bound to the air/Earth interface. Although that possibility is still being debated, the midtwentieth century saw the resurfacing of this idea with application to waves at optical frequencies bound to metal/insulator interfaces. In this regime, the surface wave is known as a surface-plasmon-polariton (SPP) wave. Within the past few decades, SPP waves have proved to be extremely valuable as a means of creating sensitive chemical sensors, especially for the detection of biochemicals [1,2]. As the ability to manipulate materials at the microscopic scale has developed, improved implementation of SPP waves with various structures and geometries continue to be proposed and realized. It is well known that the advent of nanotechnology has brought about composite materials with properties that can be quite different than those of the constituent materials in the bulk. Recent investigations [3–8] have shown that interfaces of nanostructured periodic dielectrics and metals can support SPP waves in a very novel way.