Anomalous surface plasmon dispersion in aluminum

Talk I gave at Casimir Spring School 2012

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