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SUMMARY:Modulation of THz Metamaterials Using Graphene Surface Plasmons - 
 Dr Isaac Luxmoore\, University of Exeter
DTSTART:20150216T141500Z
DTEND:20150216T151500Z
UID:TALK57720@talks.cam.ac.uk
CONTACT:Teri Bartlett
DESCRIPTION:The THz portion of the electromagnetic spectrum bridges the ga
 p between electronic and optical devices and provides a wealth of opportun
 ity for technological exploitation in areas such as free space communicati
 on\, security\, bio-sensing and trace gas detection. Metamaterials provide
  a powerful tool for the manipulation of THz radiation\, but the tunabilit
 y required for active control is difficult to achieve in predominantly met
 al based devices. Plasmonics\, on the other hand\, offers the capability t
 o confine light in subwavelength dimensions and in graphene\, the ability 
 to electrostatically control the charge density predicates tuneable and sw
 itchable devices.\n\nIn this talk\, I will first introduce graphene plasmo
 nics and demonstrate how the absorption resonances of graphene ribbons can
  be tuned dimensionally and with electrostatic gating. The importance of t
 he substrate is then highlighted with experiments which show the coupling 
 of the plasmonic resonances to surface phonons in the underlying silicon d
 ioxide [1].\n\nI will then move on to discuss hybrid metamaterials consist
 ing of graphene plasmonic resonators\, coupled to conventional split ring 
 resonators [2]. With electrostatic gating of the graphene\, up to 60% modu
 lation of the transmission is achieved and the interaction of the two reso
 nances reaches the strong coupling regime. Two peaks are observed in the t
 ransmission spectra\, which exhibit a typical anti-crossing and exchange o
 f oscillator strength. Numerical simulations provide an insight to the cou
 pled system and reproduce well the experimental observations and reveal hi
 ghly confined bonding and anti-bonding modes\, which may find applications
  in chemical and/or biological sensing. Such hybrid metamaterials can be e
 mployed as switches and modulators\, and provide a platform for exploring 
 cavity-enhanced optical processes in graphene plasmonic structures for app
 lications including sensing\, photo-detection and nonlinear frequency gene
 ration.\n\n[1] I. J. Luxmoore\, C. H. Gan\, P. Q. Liu\, F. Valmorra\, P. L
 i\, J. Faist and G. R. Nash\, ACS Photonics 1\, 1151 (2014).\n[2] P. Q. Li
 u\, I. J. Luxmoore\, S. A. Mikhailov\, S. A. Savostianova\, F. Valmorra\, 
 J. Faist and G.R. Nash\, arXiv 1501.05490 (2015).\n
LOCATION:Mott Seminar Room (Mott Building Room 531)\, Cavendish Laboratory
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