April 2, 2008
FRONTIERS IN MATERIALS SCIENCE
VINSE COLLOQUIUM SERIES
Dr. Teri Odom
Associate Professor of Materials Science and Engineering
"Multiscale Pattering of Plasmonic Metamaterials"
Abstract. The interaction of light with surface plasmons—collective oscillations of free electrons—in metallic nanostructures has resulted in demonstrations of enhanced optical transmission, collimation of light through a subwavelength aperture, and negative permeability and refraction at visible wavelengths. The structures that display these phenomena typically consist of ordered arrays of particles or holes with sizes of the order 100 nm. Surface plasmons can interact with each other over much longer distances, however, and thus the ability to organize nanoscale particles or holes over multiple length scales could lead to new plasmonic metamaterials with novel optical properties. This talk will describe a multi-scale patterning approach based on soft lithography to create such plasmonic metamaterials. Gold films perforated with quasi-infinite arrays of 100-nm holes were generated over areas greater than 10 cm2, exhibiting sharp spectral features that changed in relative amplitude and shifted to longer wavelengths when exposed to increased refractive index environments. Such metal materials systems exhibited dispersion diagrams analogous to electronic materials; moreover, the origin of their complex spectra can be described by a new optical coupling mechanism. Furthermore, when gold nanohole arrays were patterned into microscale patches, they exhibited strikingly different transmission properties and appeared to focus light. We will also describe the optical properties of various infinite and finite-area arrays of nanoparticles, including optically distinct particles patterned side-by-side and those that contain both metallic and dielectric materials.