Fractal Plasmonic Nanoantennae

The ability to precisely tailor lineshapes, operational bandwidth and localized electromagnetic field enhancements (“hot spots”) in nanostructures is currently of interest in advancing the performance of plasmonics based chemical and biological sensing techniques as well as in plasmonics based energy harvesting applications. Fractal geometries are an intriguing alternative in the design of plasmonic nanostructures as they offer tunable multi-band response spanning the visible and infrared spectral regions. This chapter reviews the recent developments concerning the incorporation of fractal geometries into plasmonic nanostructures. The scope is restricted to the review of fractal shaped antenna elements as opposed to fractal based array placement methods. Beginning with a brief overview of fractals and fractal based radio-frequency antenna engineering, the review focuses on two canonical geometries: the Sierpinski carpet and the fractal tree. Fractal geometries are promising for improving the performance of plasmonics based optical applications like ultrasensing and energy harvesting.