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Q-Han Park Korea Univ.

Q-Han Park Korea Univ. APSE 2010. Electromagnetic field enhancement in nano optics. The 4 th Yamada Symposium on Advanced Photons and Science Evolution 2010. EM field enhancement - antennas. Monopole antenna. Marconi's antenna system at Poldhu Cornwall, December 1901.

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Q-Han Park Korea Univ.

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  1. Q-Han Park Korea Univ. APSE 2010 Electromagnetic field enhancement in nano optics The 4th Yamada Symposium on Advanced Photons and Science Evolution 2010

  2. EM field enhancement - antennas Monopole antenna Marconi's antenna system at Poldhu Cornwall, December 1901.

  3. Antenna - receiver Frequency independent antenna Yagi antenna Horn antenna at Bell Labs, Holmdel, NJ that Penzias and Wilson used to discover the 3 K cosmic microwave background radiation in 1965.

  4. Nano-optical antenna 21 C. 20 C. Optical antenna Radio/microwave 1900 1945 21st century m Marconi RF antanna Cell Phone New frontier: human to nanoworld Radar mm Nanooptics SERS Cancer LED Solarcell : Opt. Ant. : humanto human nm

  5. Optical antenna-monopole Bring it down to the optical regime ! N.F. van Hulst group, NanoLett. 7,28, 2006 nature photonics, 2008 Optical monopole antenna

  6. Optical antenna - sensor Optical monopole antenna Single molecule fluorescence Excitation 514 nm Fluorescence 570 nm Emission control by a monopole antenna

  7. Optical antenna as a vector field probe D.S.Kim, Q.Park.et al, Nature Photonics 1, 53 (2007)

  8. Nano metal particles • dipole plasmon resonance Transmission, bio-sensing, cancer therapy N. Halas group • 128 nm core diameter, 14 nm gold shell, • peak absorbance at 820 nm • 10 degree Temp increase S.Cho, Q.H.Park, Angew. Chem.Int. 2007

  9. Metallic nano structures SP enhanced PL SERS, silver nanorod+plate J.Joo, Q.H.Park, Adv. Mater. 2007 Dodecahedron B.Kim, Q.H.Park, JACS, 2007; JACS 2009 S.W.Han, Q.H.Park, JACS. 2009

  10. Optical antenna - bowtie

  11. Bow tie antenna – EUV generation S.W.Kim et al, Nature 2008

  12. Bow tie antenna S.W.Kim et al, Nature 2008

  13. Terahertz – nano Terahertz field enhancement by a metallic nano slit operating beyond the skin-depth limit D.S.Kim, Q.Park et al. Nature Photonics 3, 152, 2009

  14. EM field enhancement by nano slit Electric field enhancement: ~1,000 with λ /10,000 size gap

  15. Diffraction theory claculation Mordal expansion

  16. Boundary matching Mode Coupling Strength W:

  17. Field enhancement Mordal method vs. FDTD numerical method Ex field at x=a/2, z=h/2 width = 0.0002 thickness = 0.002 Good quantitative predictions, but only good for global/specific geometry

  18. Local capacitor model Local Capacitor Model for Plasmonic Electric Field Enhancement Q.Park Phys. Rev. Lett.102, 093906, 2009 l-zone

  19. Slit l-zone capacitance Static capacitance restricted to the l-zone

  20. Conformal mapping

  21. Enhanced electric field inside the gap width = 0.00067 thickness = 0.002

  22. Real metal case Good qualitative agreement

  23. Metal tip near metal surface y Intensity profile near metal tip (FDTD calculation:xy-cut) x z y-polarized incident light xz-cut

  24. Bowtie Spheroidal prolate coordinates Field enhancement

  25. Static potential Prolate spheroidal coordinates tip surface: v = v0.

  26. Prolate spheroidal coordinates specify the shape of a hyperboloid tip by v = v0.

  27. Induced current/charge Surface current in the back side

  28. LCM for a metal tip ν0=π/6

  29. Half wave dipole antenna l/2 H E Slot antenna Slot antenna Resonantly enhanced radiation

  30. THz slot antenna Near field imaging of terahertz focusing onto rectangular apertures D.S.Kim, P. Planken, Q.Park, Optics Express 16,20484, 2008

  31. Fourier transform terahertz imaging of E_x

  32. Energy Funneling: constant energy

  33. Substrate effect Substrate effect on aperture resonances in a thin metal film J. H. Kang, J.H. Choe, D.S. Kim, Q. Park, Optics Express 17,15652, 2009

  34. Substrate effect

  35. Resonance Transmission at resonance

  36. Phased array antenna X-Band Phased-Array Antenna

  37. Extraordinary Optical Transmission ~ 5%! SEM r = 100 nm, p = 800 nm, t = 300 nm, Au on sapphire T. W. Ebbesen et al., Nature 391, 667-669 (1998)

  38. Various slots for terahertz frequencies At terahertz, metals are lossless: d/l~1/1000; wavelength: 0.1 mm~10 mm, skin depth=100 nm, Shape resonance omni-directional terahertz filters with near-unity transmittance D.S. Kim et al. Opt. Expr. 14,1253,(2006) SEM or Microscopic Images 0.5 mm

  39. Perfect transmission

  40. Optical Yagi-Uda Antenna Directional control of light by a nano-optical Yagi–Uda antenna Terukazu Kosako1, Yutaka Kadoya, Holger F. Hofmann, NATURE Photon, March, 2010

  41. Conclusions Photonic crystal, metamaterial, optical antenna,… • Learn from analogies • receive and transmit • enhance and focus electric field • Directivity • Phased array • Learn from differences • can be active -- lasing • nonlinear optical processes • communicates with nano world: • - controlled chemistry/biology • more to come

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