PHYSICS/BK21 Colloquium[09.12.4]

                
           “Doubly Terahertz Nano Metamaterials”

  
Ø* Speaker : Prof. Dae Sik Kim [Seoul National University]    
Ø* Place : Demonstration Lecture Hall 122,  Postech Information Research Laboratories
Ø* Date & Time :  Dec,  4(Fri)  4:00 ~ 5:00 pm

  
ØAbstract
  
  
Thin layers of semiconductors, superconductors, correlated electron systems, and polymers are the
core elements of modern science and technology. Metamaterials research also heavily utilizes thin
films, nonlinear index increases of which caused by photo-excitation, voltage, or temperature have
been used to actively control technologically important  long  wavelength  electromagnetic  waves.
These control attempts are however met with only partial success, because the l/1,000 ~ l/100,000
films are optically too thin even considering the large dielectric constants, and  also  because  the
Control  has  limited  spectral  range  around  resonance.  Here,  we  show  that  broadband,  long
wavelength nano  antennas  on  VO2  (vanadium dioxide) films,  initially  transparent  to  incoming
electromagnetic waves, achieve a 100,000 to 1 extinction by phase transition  of  the  underlying
thin film, thereby increasing the dielectric constant to over 500,000. Our scheme, utilizing strongly
evanescent wavevector components below the nanoscale features, offering orders of magnitudes
tenability of nonlinearities and dielectric constants, bridges the gap between thin film technology,
nanotechnology, and active metamaterials researches.

             Contact Person : Prof. Dong-Eon Kim(054-279-2089, kimd@postech.ac.kr)