Contact: Dr. Abebe Kebede
336-285 2113 or email

  Dr. David Aspens

Dr. David E. Aspens

North Carolina State University
Raleigh, NC 27695-8202
Website: URL

Prof. Aspnes heads the Real-Time Diagnostics and Control Laboratory, and has published over 300 papers with primary emphases in the areas of optical spectroscopy and of semiconductor and surface physics. Contributions include the discovery, elucidation, and development of low-field electroreflectance for high-resolution spectroscopy of semiconductors and the determination of their band structures, the development and application of spectroscopic ellipsometry to the analysis of surfaces, interfaces, thin films, and bulk materials, and the development and application of reflectance-difference spectroscopy for the real-time analysis of epitaxial growth. Current research activities are directed toward nondestructive analysis of surfaces, interfaces, and bulk materials, including properties of GaN, high precision determination of energy band critical points by reciprocal space analysis, properties of Si surfaces and interfaces, propagation of short optical pulses, and the development of experimental and theoretical methods of realizing real-time diagnostics and control of semiconductor epitaxy by organometallic chemical vapor deposition.
  November 17, 2008

Marteena Hall, Room 310  Time- 4:00 PM

Title: Optical and Electrodynamic Phenomena in Metamaterials

Materials that are composites of other materials on length scales ranging from nanometers to microns show a wide range of optical and electromagnetic properties that do not occur in their uniform constituents.  These include for example quantum-confinement shifts of absorption edges, effective-medium descriptions of dielectric responses, plasmon/polariton resonances, photonic band structure, and negative refractive indices with the associated properties of subwavelength imaging and "invisibility".  In addition to their scientific interest, many of these effects are becoming significantly important in technology.  Here, I present an overview of the topic, discuss how these properties can be understood from a fundamental perspective, and show that in some cases the associated mathematics is surprisingly simple.