Anomalous surface plasmon dispersion in aluminum

Anomalous surface plasmon dispersion in aluminum

Talk I gave at Casimir Spring School 2012

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Philip Chimento

June 15, 2012
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Transcript

  1. Anomalous surface plasmon dispersion in aluminum Eric Eliel Gert ‘t

    Hooft Philip Chimento >ĞŝĚĞŶhŶŝǀĞƌƐŝƚLJͻYƵĂŶƚƵŵKƉƟĐƐ @therealptomato { }
  2. { Surface plasmons }

  3. Quick explanation of them Surface plasmons Using English literature

  4. in English literature Image: public domain Surface plasmons Dr. Edwin

    Abbott Abbott, author of...
  5. “Flatland”

  6. “Flatland” A surface plasmon polariton is what a light wave

    would be in Flatland
  7. “Flatland” A surface plasmon polariton is what a light wave

    would be in Flatland
  8. Exist on the interface between a metal and a dielectric

    Surface plasmons
  9. Can be excited using light, but not directly Surface plasmons

  10. Can be excited using light, but not directly Surface plasmons

  11. A surface plasmon on a metal-air interface has more momentum

    than a photon with the same energy in air Surface plasmons
  12. A photon in a denser medium can match the momentum

    of a surface plasmon on a metal-air interface Surface plasmons
  13. Attenuated total reflection — “Kretschmann configuration” ATR Coupling

  14. Evanescent waves from the total internal reflection cross the metal

    and couple to plasmons on the other side ATR Coupling
  15. { That was easy }

  16. It’s a question of “the least bad” Metals for plasmonics

  17. Aluminum is one of the “least bad” Metals for plasmonics

  18. Rakic et al., Appl. Opt. 37, p. 5271 (1998) Aluminum

    has an interband transition that absorbs at 800 nm Aluminum
  19. E ective mode index of plasmons on an aluminum surface

    Aluminum plasmons īĞĐƟǀĞ^WŝŶĚĞdž
  20. have a region of anomalous dispersion Aluminum plasmons īĞĐƟǀĞ^WŝŶĚĞdž Anomalous

      dispersion
  21. Experiment Exciting plasmons on aluminum by ATR coupling ϱŶŵ^ŝ 3

    N 4   ƉƌŽƚĞĐƟŽŶůĂLJĞƌ ϳ͕ϵ͕ϭϮ͕ϭϯŶŵů <ϳŐůĂƐƐ
  22. Measure reflection as a function of angle Experiment    

                                             ^ŽƵrĐe                                                                                                                                                                                                              DeteĐtŽr                    ɽ                                  ɽ
  23. We measure hundreds of one-wavelength curves like these... Experiment

  24. ...to get a dispersion curve like this Experiment īĞĐƟǀĞ^WŝŶĚĞdž

  25. The results were less than inspiring for a 9 nm

    layer Plasmon dispersion
  26. For a 12 nm layer, the dispersion was anomalous but

    less than expected Plasmon dispersion īĞĐƟǀĞ^WŝŶĚĞdž
  27. Novotny et al., J. Nanophotonics 5 (2011) Thin-layer aluminum doesn’t

    have the same optical properties as bulk aluminum What’s going on? ďƵůŬ
  28. Thicker aluminum layer behaves more like bulk aluminum, but diminishes

    the ATR e ect How to fix it?
  29. Thicker aluminum layer behaves more like bulk aluminum, but diminishes

    the ATR e ect How to fix it? The evanescent waves evanesce before they reach the top
  30. You have to be crazy to do it, but: the

    Otto configuration How to fix it?
  31. Crazy? Relative size of a dust particle, 20 µm Gap

    size, 1 µm
  32. Luckily, that problem is solvable How to fix it? ŚŝŐŚͲŝŶĚĞdžĚŝĞůĞĐƚƌŝĐ

    ůŽǁͲŝŶĚĞdž ĚŝĞůĞĐƚƌŝĐ
  33. { Thanks } Fruitful discussions Michiel de Dood Wolfgang Lö

    er Kind assistance Daan Boltje Klara Uhlirova