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

Scientific talk I gave at Physics@FOM Veldhoven 2012.

Transcript

1. A Circular Nanoslit as a Spin-to-Orbital Angular Momentum Converter Philip Chimento Gert ‘t Hooft Eric Eliel
2. Suspicious behavior in subwavelength slits
3. Chimento, Kuzmin, Bosman, et al. (2011). Opt. Expr. 19 (24), 24219. Slit in a metal film
4. Chimento, Kuzmin, Bosman, et al. (2011). Opt. Expr. 19 (24), 24219. Slit in a metal film Subwavelength in one direction “Infinite” in the other
5. Chimento, Kuzmin, Bosman, et al. (2011). Opt. Expr. 19 (24), 24219. Almost ideal metal TM TE Slit width in λ
6. Chimento, Kuzmin, Bosman, et al. (2011). Opt. Expr. 19 (24), 24219. Real metal TM TE Slit width in λ
7. Chimento, Kuzmin, Bosman, et al. (2011). Opt. Expr. 19 (24), 24219. Real metal If designed carefully, there is a point where the slit is a quarter-wave plate Analyzer rotation Input state Measured output
8. Photo credit: Dandelion And Burdock, Flickr We roll the slit up into a circle
9. Space-variant λ/4 plate
10. Space-variant λ/4 plate TM TM TE TE
11. Space-variant λ/4 plate Input: circular polarization σ+ state
12. Space-variant λ/4 plate Output: ?
13. Transmitted polarization state Schematic
14. Transmitted intensity Experiment
15. Transmitted polarization state Left-handed elliptical Right-handed elliptical Ellipticity <10% Experiment
16. Photo credit: Cayusa, Flickr Where did the spin angular momentum disappear to?
17. Cylindrical symmetry means no angular momentum is transferred to the plate Photo credit: pixaio, sxc.hu
18. Fascinating! What does the far field look like?
19. Far field Angle Angle Intensity (arb. units)
20. Far field Angle Angle Intensity (arb. units) No hole in the middle!
21. Far field Component with the same handedness as the input (σ+) Component with opposite handedness to the input (σ−)
22. Phase of central spot Component with the same handedness as the input (σ+) Component with opposite handedness to the input (σ−)
23. A proper calculation mode con- verter ￿ѫ +,￿ = ￿ ￿ѫ+ ,￿ = ￿ ￿ѫ −,￿ = ￿
24. A proper calculation mode con- verter ￿+TQJO￿ = −￿ I ￿+PSCJU￿ = ￿ I ￿+TQJO￿ = +￿ I ￿+PSCJU￿ =  ￿ѫ +,￿ = ￿ ￿ѫ+ ,￿ = ￿ ￿ѫ −,￿ = ￿
25. A proper calculation mode con- verter ￿+TQJO￿ = −￿ I ￿+PSCJU￿ = ￿ I ￿+TQJO￿ = +￿ I ￿+PSCJU￿ =  Total angular momentum remains the same! ￿ѫ +,￿ = ￿ ￿ѫ+ ,￿ = ￿ ￿ѫ −,￿ = ￿
26. We found, constructed, and understood a novel spin-to-orbit angular momentum coupling device.
29. Orbital angular momentum ⟨Jspin ⟩ = 0 ⟨Jorbit ⟩ = ̵ h