|
SINAM Nano-Seminar Announced Nano-Seminar Series - 4 seminars on April 12 1. Dr. Francisco Garcia-Vidal - University of Madrid, Spain 2. Dr. Yanfeng Cheng - Nanjing University - Title TBA 3. Dr. Teruya Ishihara - RIKEN, Japan 4. Dr. Won Park - University of Colorado at Boulder Thursday, April 12, 2007 All seminars will be approximately 35 minutes, with 5-10 minutes for discussion.
ABSTRACTS AND BIOGRAPHIES 1. The pioneering experiment of Ebbesen et al. [1] showing that light can be efficiently transmitted through a 2D array of subwavelength holes perforated on optically thick metal films has opened a new area of research within Optics. We will show how the physical origin of this phenomenon relies on the excitation of surface plasmons at the metal surfaces, opening the way of finding many interesting phenomena associated with the properties of these surface electromagnetic (EM) resonances. Then, we will discuss the enhanced optical transmission phenomenon and beaming effects observed in single subwavelength apertures (holes or slits) flanked by periodic corrugations. We will also see how a 2D array of subwavelength holes drilled in a perfect conductor gives rise to a similar extraordinary transmission even though the free surface of an unperforated perfect conductor has no surface modes. We will demonstrate that there are not two separate mechanisms: the holes will spoof surface plasmons which play the same resonant role as the real ones on silver or gold in the optical regime. We will export this spoof plasmon concept to a periodically corrugated metal wire with the idea of guiding and focusing light in the THz or microwave ranges of the EM spectrum. BIO: Prof. Francisco J. Garcia-Vidal obtained his PhD in 1992 at the Condensed Matter Theory group at Universidad Autonoma of Madrid (Spain). The subject was chemisorption of hydrogen in metal and semiconductor surfaces. From 1994 to 1996 he worked as a post-doc with John Pendry at Imperial College and they begin to work on the subject of surface plasmons. Since 1997, he leads a theoretical team at the Universidad Autonoma of Madrid devoted to investigate, from a fundamental point of view, the optical properties of structured metal surfaces. 2. TBA 3. When the light excite a periodic structure, reflection , refraction and diffraction take place in general. As photons carry momentum, shear force can be given to the structure. In periodic structure made of good metal, free eletrons receive this force. 4. Photonic crystal and metamaterial structures provide a powerful means to control and engineer electromagnetic wave propagation. Photonic crystal uses a periodic structure that gives rise to Bragg reflections and consequently strongly modulated Bloch waves. Proper designs of photonic crystal structure can make them exhibit negative refractive index, super-collimation and extreme anisotropy. When the periodicity becomes much smaller than the wavelength, photonic crystal behaves like a homogeneous medium, which is often referred to as metamaterial. By embedding deep sub-wavelength resonators in metamaterials, one may produce magnetic activity at optical frequencies and negative index of refraction. In this talk, I will present experimental demonstrations of negative index of refraction, super-collimation and giant walk-off in Si-based photonic crystal structures in the near-infrared frequency region. Also presented will be some device applications of the Si photonic crystals and a novel cluster photonic crystal design that could give rise to optical frequency magnetism. BIO: Dr. Wounjhang Park is an assistant professor of Electrical & Computer Engineering at University of Colorado at Boulder. He received his Ph.D. degree from the Georgia Institute of Technology in 1997. He then worked at the Georgia Tech Research Institute as Post-Doctoral Fellow and Research Scientist II until he joined the University of Colorado at Boulder in 2001. At Georgia Tech, he was an active member of the Phosphor Technology Center of Excellence and conducted a highly productive research on luminescent materials and flat panel display devices. His current research interests are primarily in the development of novel photonic nanostructures such as photonic crystals, metamaterials and plasmonic materials for nanophotonics and biophotonics applications. Dr. Park has authored over 70 peer-reviewed technical articles and an invited book chapter. He is currently serving as an editorial board member of the Journal of Computational and Theoretical Nanoscience. View the flyer for this event (PDF, 21KB) Seminar presented by the Center for Scalable and Integrated Nanomanufacturing
|