UC San Diego

One of the characteristics of dealing with photons is that many interesting and potentially useful optical phenomena happen on the scale of the wavelength or smaller. The interaction of light with structures in this size range has garnered a great deal of attention in the past few years, and has been aptly named 'Nanophotonics'. One of the goals in this field is to study the behavior of different material systems at the nanoscale, in order to create new photonic applications in different disciplines. Metal structures have been used as optical reflectors for many centuries. However metals are not only good reflectors of light. As we shall see, they have properties similar to a collection of free electrons with negative permittivity. This unique characteristic leads to extraordinary optical properties, which are collectively called 'plasmonic' and has led to the development of a corresponding branch of photonics, called 'Plasmonics'. In this work we will be focusing on various properties and applications of plasmonic materials and devices. We start by reviewing the basic properties of metals together with their plasmonic and optical characteristics. Following that we investigate the properties of metal gratings, with special attention given to subwavelength metal gratings and their application to polarization control. Also two novel devices based on these gratings are introduced. Then we address the propagation of surface plasmon polaritons on metal slabs and stripes. Specifically, the long range plasmon polarition modes are investigated theoretically and experimentally. Fabrication approaches for making devices that utilize these modes are presented together with optical characterization results. In addition, the propagation of surface plasmon polaritons in the vicinity of an optical gain medium is treated theoretically. Also, the properties of various gain media are reviewed and the practical implementation of gain assisted plasmonic devices is discussed. We also revisit the use of metals as reflection devices and discuss their application for creating subwavelength resonators. Using the results of this study, resonant nanoscale structures are proposed with the goal of creating nanoscale lasers emitting in the near infrared. In continuation, we explore the optical properties of metals at low temperatures, both theoretically and experimentally. The ellipsometric measurements carried out in this context suggest that it may be possible to enhance the plasmonic properties of metals by cooling them to cryogenic temperatures