Nanosphere Lithography to Enable Plasmonic Applications pp.195-243
Authors: (Yue Bing Zheng, Tony Jun Huang, Department of Engineering Sciences and Mechanics, The Pennsylvania State University, University Park, Pennsylvania
Abstract: Surface plasmon-based photonics, or “plasmonics”, combines the capacity of photonics with the miniaturization of electronics, thereby merging photonics and electronics at nanoscale dimensions. Fundamental research in plasmonics benefits applications such as nanophotonic integrated circuits, biological sensing and imaging, selective photothermal therapy, perfect lenses, and electromagnetic cloaks. To realize these applications, fabrication of plasmonic nanostructures is the first and one of the most significant challenges to overcome. This challenge entails the development of costeffective and high-throughput methods to produce plasmonic nanostructrues that are tailorable and scalable for various applications. Nanosphere lithography (NSL) is a lowcost and high-throughput method of nanofabrication, where self-assembled layers of nanospheres serve as templates or masks in the production of ordered nanostructure arrays. This chapter discusses the authors’ recent work in NSL to produce ordered arrays of plasmonic nanostructures with various morphologies: prisms, rings, caps, disks, holes, and wires. The localized surface plasmon resonances (LSPR) of two such arrays – Au/TiO2 core/shell nanoprism arrays and Au nanodisk arrays – were investigated experimentally and theoretically. The arrays exhibited LSPR of high intensity and narrow bandwidth that was further tailored by controlling the structures’ geometric parameters (their shapes and sizes), the topologies of the substrates, and the refractive indices of the surrounding media. Furthermore, the authors demonstrated an application of such nanostructures in an all-optical plasmonic switch based on Au nanodisk arrays and photoresponsive liquid crystals. It is likely that due to the low cost and high throughput in the nanofabrication process along with their high-quality, engineerable plasmonic characteristics, these plasmonic nanostructure arrays can be established as an excellent platform for both fundamental research and engineering applications in plasmonics.