Metamaterials introduction ppt

ppt on metamaterials and metamaterials ppt powerpoints
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Dr.GriffinWood,United Kingdom,Teacher
Published Date:23-07-2017
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Introduction to Metamaterials Richard D. Averitt Research Themes “Equilibrium  is  when  all  of  the  fast  stuff  has  happened,  and  all  of  the  slow  stuff  hasn’t.”   -­‐Feynman  Metamaterials: a new field D. R. Smith, et al., Phys. Rev. Lett. 84, 4184 (2000) J. B. Pendry, A. J. Holden, D. J. Robbins, W. J. Stewart, “Magnetism from conductors and enhanced non-linear phenomena,” IEEE Trans. MTT 47, 2075 (1999) The Irresistible Fantasy of the Invisible Man, and Machine New  York  Times,  2007  The Chameleon The Stealth Fighter: Invisible to Radar? Very small radar cross section: shape and absorbing paint A camera and a projector From:  http://www.star.t.u-­tokyo.ac.jpFantastic 4: The Invisible Woman by  Lee  &  Kirby  (1961) "...  she  achieves  these  feats  by   bending  all  wavelengths  of  light  in   the  vicinity  around  herself  ...   without  causing  any  visible   distortion.” -­-­ Introduction  from   WikipediaThe Invisible Man by H.G. Wells (1897) "...  it  was  an  idea  ...  to  lower  the   refractive  index  of  a  substance,   solid  or  liquid,  to  that  of  air  — so   far  as  all  practical  purposes  are   concerned.” -­-­ Chapter  19   "Certain  First  Principles" Key  Concept:    The  Refrac2ve  Index  à  n     Velocity  of  light  in  free  space:  c   In  a  material:  c/n    Mirage: Optical Illusion The  bending  of  light  due  to  the  gradient  in  refractive  index   in  a  desert  mirageTearing  Space:  conformal  map   We  can’t  tear  space:     Mimic  by  shaping   the  refrac2ve  index  n     Wegner,  Linden  in  Physics  Today,  2010  The  New  York  Times;  3-­‐D  model  by  Christoph  Hormann  and  Gunnar  Dolling,  Karslruhe  University  Snell’s  Law •  Reflection: θ = θ i r •  Refraction: n sinθ =n sinθ 1 i 2 t The refraction beam is at the other side of the incident normal. NegaUve  RefracUve  Index:  A  long  history   •  A.  Schuster,  An  IntroducUon  to  the  Theory  of  OpUcs,  (1904)          -­‐  Discussed  in  the  context  of  anomalous  dispersion  as  occurs  at  any  absorpUon  band.   •  L.I.  Mandelshtam,  May  5  1944  (last  lecture)   In fac t, the direction of wave propagation is determined by its phase velocity, while energy is transported at the group velocity. - Translated by E. F. Keuster PosiUve  RefracUon   X. Huang, W. L. Schaich, Am. J. Phys.72, 1232 (2004) NegaUve  RefracUon   X. Huang, W. L. Schaich, Am. J. Phys.72, 1232 (2004) Sir  John  Pendry  –  leading  theorist  in   the  area:   In  convenUonal  materials,  the  dielectric  response  derives  from  the  consUtuent   atoms.  As  discussed,  negaUve  or  posiUve  ε(ω)  is  possible  over  a  broad  spectral   range.  However,  natural  materials  with  a  resonant  magneUc  permeability  µ(ω)   dont  exist  above  a  few  THz  (e.g.  FerromagneUc  resonance  in  Fe  at  microwave   frequencies,  or    anUferromagneUc  resonance  in  MnF  at  2THz).   2 Pendry,  Contemporary  Physics  Metamaterials: Expanding our Space -25 -30 Pendry et al. suggested that an array of ring -35 resonators could respond -40 to the magnetic -45 component light.   -50 -55 4.7 4.8 4.9 5 5.1 5.2 5.3 5.4 5.5 Frequency (GHz) J. B. Pendry, A. J. Holden, D. J. Robbins, W. J. Stewart, “Magnetism from conductors and enhanced non-linear phenomena,” IEEE Trans. MTT 47, 2075 (1999). Transmitted Power (dBm)LCR  circuits   •  A  circuit  with  an  inductor  (L)  and  capacitor  (C)   saUsfies  the  same  equaUon  as  the  mass  spring   system  for  simple  harmonic  oscillaUon.   •  If  we  added  a  resistor  (R)  that  we  get  the   damped  oscillator  equaUon.   –  as  for  the  mechanical  oscillator,  the   soluUon  can  be     •  under  damped:      (  γ      2  ω  )   0 •  criUcally  damped:    (  γ    =    2  ω  )     0 •  over  damped:      (  γ        2  ω  )   0 •  We  can  choose  the  values  of  L,  C,  and  R  to   determine  which  kind  of  damping  we  have.  Comparison  between  mass-­‐spring  systems  and  LCR  circuits.