Radiation Nanofocusing Using Tapered Metal Gaps
|Event Date:||April 19, 2010|
|Speaker Affiliation:||Institute of Sensors, Signals and Electrotechnics(SENSE);
University of Denmark
|Sponsor:||Nanotechnology Seminar Series|
|Location:||MRGN Room 129|
|Contact Name:||Prof Vladimir Shalaev
|Open To:||ACCEPTABLE FOR ECE694A
Nanofocusing of electromagnetic radiation, i.e. its concentrating well below the diffraction limit, is one of the most fundamental, yet rich with prospective applications, research directions in optics, in general, and in plasmonics, in particular. After briefly reviewing various options for nanofocusing in free space by using near-field phase conjugation , linking it to the recent developments in nanofocusing  and cloaking , the radiation nanofocusing by making use of suitable surface plasmon (SP) modes supported by metal waveguides, i.e. the SP modes that scale down in size linearly with the waveguide cross section, is discussed. Nanofocusing of channel plasmon polaritons (CPPs), which are SP modes supported by grooves cut into metal, is considered in detail, not only presenting the underlying physics involved but also reporting on design, fabrication, characterization and modelling of radiation CPP nanofocusing with subwavelength gold grooves being gradually tapered synchronously in depth and in width. Efficient CPP nanofocusing at telecom wavelengths with the estimated field intensity enhancement of up to ~ 90 is directly demonstrated using near-field microscopy and careful electromagnetic simulations predict more than 1000-fold intensity enhancements , opening thereby exciting perspectives for practical exploitation of the CPP-based nanofocusing. Another promising approach is to actually implement an original idea by Nerkararyan  of radiation focusing in tapered gaps, an approach that allowed us to achieve the intensity field enhancement of ~100 at the gold groove bottom (under normal illumination) . Further developments and possible applications of the plasmonic nanofocusing phenomena are also discussed.
Sergey I. Bozhevolnyi (born in 1955) has received the degrees of M.Sc. in physics (1978) and Ph.D. in quantum electronics (1981) from the Moscow Physical Technical Institute, a.k.a. “FizTech”, and Dr.Scient. from Aarhus University, Denmark (1998). He joined the Department of Physics and Nanotechnology, Aalborg University (Denmark) in 1991, becoming a professor in physics in 2003. Since February 2008 he is a professor in nano-optics at the University of Southern Denmark (Odense), heading research activities within plasmonics and near-field optics. His research interests include linear and nonlinear nano-optics, surface plasmon polaritons and nano-plasmonic circuits, multiple light scattering including photonic band gap and light localization phenomena, photonics and optical sensors. Plasmonics with implications to nanophotonics and bio- and molecular sensing is his main current research field. He has (co-) authored more than 240 scientific publications in peer-reviewed journals (citations > 4300, h = 33), 10 patents and 9 book chapters, edited a book “Plasmonic Nano-Guides and Circuits” (Word Scientific, Singapore, 2008) and gave more than 80 invited talks at international conferences and seminars. Prof. Bozhevolnyi has supervised 8 postdocs and 15 PhD projects, and is a Fellow of the Optical Society of America.