A Circular Nanoslit as a Spin-to-Orbital Angular Momentum Converter

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Scientific talk I gave at Physics@FOM Veldhoven 2012

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A Circular Nanoslit as a Spin-to-Orbital Angular Momentum Converter

  1. 1. A Circular Nanoslit as aSpin-to-Orbital AngularMomentum ConverterPhilip ChimentoGert ‘t HooftEric Eliel
  2. 2. Suspiciousbehavior insubwavelengthslits
  3. 3. Slit in a metal filmChimento, Kuzmin, Bosman, et al. (2011). Opt. Expr. 19 (24), 24219.
  4. 4. Slit in a metal film Subwavelength “Infinite” in the other in one directionChimento, Kuzmin, Bosman, et al. (2011). Opt. Expr. 19 (24), 24219.
  5. 5. Almost ideal metalTM TE Slit width in λChimento, Kuzmin, Bosman, et al. (2011). Opt. Expr. 19 (24), 24219.
  6. 6. Real metalTM TE Slit width in λChimento, Kuzmin, Bosman, et al. (2011). Opt. Expr. 19 (24), 24219.
  7. 7. Real metal Input state Analyzer rotation Measured output If designed carefully,there is a point where theslit is a quarter-wave plateChimento, Kuzmin, Bosman, et al. (2011). Opt. Expr. 19 (24), 24219.
  8. 8. We roll the slit up into a circlePhoto credit: Dandelion And Burdock, Flickr
  9. 9. Space-variant λ/4 plate
  10. 10. Space-variant λ/4 plate TE TM TM TE
  11. 11. Space-variant λ/4 plateInput: circular p olarization σ+ state
  12. 12. Space-variant λ/4 plate Output: ?
  13. 13. Transmitted polarization state Schematic
  14. 14. Transmitted intensity Experiment
  15. 15. Transmitted polarization state Experiment Left-handed elliptical Right-handed elliptical Ellipticity <10%
  16. 16. Where did the spin angular momentum disappear to?Photo credit: Cayusa, Flickr
  17. 17. Cylindrical symmetry means no angular momentum is transferred to the plate Photo credit: pixaio, sxc.hu
  18. 18. Fascinating!What does the far field look like?
  19. 19. AngleAngle Far field Intensity (arb. units)
  20. 20. Far field No hole in Intensity (arb. units) the middle!Angle Angle
  21. 21. Far field Component with the same Component with oppositehandedness as the input (σ+) handedness to the input (σ−)
  22. 22. Phase of central spot Component with the same Component with oppositehandedness as the input (σ+) handedness to the input (σ−)
  23. 23. A proper calculation +, = +, = mode con- −, verter =
  24. 24. A proper calculation +, = +, = mode = + con- verter −, = = = − =
  25. 25. A proper calculation +, = +, = mode = + con- verter −, = = = − Total angular momentum remains the same! =
  26. 26. We found,constructed, andunderstood a novelspin-to-orbit angularmomentum couplingdevice.
  27. 27. Orbital angular momentum ⟨Jspin ⟩ = 0 ̵ ⟨Jorbit ⟩ = h

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