Design and Implementation of Plasmonic Cavities in Thin Metallic Films

Download or read book Design and Implementation of Plasmonic Cavities in Thin Metallic Films written by John Liu (Photovoltaics engineer) and published by Stanford University. This book was released on 2010 with total page 97 pages. Available in PDF, EPUB and Kindle. Book excerpt: Metals contain a sea of free electrons that are easily driven into collective oscillation by electromagnetic waves. As a result, small metal objects can serve as antennas that strongly scatter light. At the same time, extended metal surfaces have been shown to guide surface plasmons (photons bound to surface charge oscillations) that can confine light to deep sub-wavelength dimensions. Patterned metallic films can combine both the scattering and guiding properties of metals to capture and concentrate light from free space into a photodetector or to control the emission of light from emitting media. We first consider the wide range of functions that can be achieved in directing light emission with the help of smooth metallic films. We then describe how light interacts with patterned metallic films and present a detailed study of the effect of a single metallic groove on the scattering and surface plasmon guiding processes. This has lead to our discovery of new, exciting opportunities for dense optical functionality with non-periodically patterned metallic films. We show that a micronscale structure consisting of just two grooves in a metal film can lead to directional light coupling and wavelength splitting with a contrast ratio of 3:1. Our understanding is then generalized giving rise to a fast, simplified optimization of large non-periodic structures for a desired function. Lastly we consider the efficiency and bandwidth limits of coupling light through sub-wavelength slits for photodetection. We outline a path to efficient, spectrally selective detection which may find application in compact, polarization sensitive, multi-wavelength plasmonic detectors.