A Circular Nanoslit as a
Spin-to-Orbital Angular
Momentum Converter
Philip Chimento
Gert ‘t Hooft
Eric Eliel
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Suspicious
behavior in
subwavelength
slits
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Chimento, Kuzmin, Bosman, et al. (2011). Opt. Expr. 19 (24), 24219.
Slit in a metal film
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Chimento, Kuzmin, Bosman, et al. (2011). Opt. Expr. 19 (24), 24219.
Slit in a metal film
Subwavelength
in one direction
“Infinite” in the other
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Chimento, Kuzmin, Bosman, et al. (2011). Opt. Expr. 19 (24), 24219.
Almost ideal metal
TM
TE
Slit width in λ
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Chimento, Kuzmin, Bosman, et al. (2011). Opt. Expr. 19 (24), 24219.
Real metal
TM
TE
Slit width in λ
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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
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Photo credit: Dandelion And Burdock, Flickr
We roll the slit up
into a circle
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Space-variant λ/4 plate
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Space-variant λ/4 plate
TM
TM
TE
TE
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Space-variant λ/4 plate
Input: circular polarization
σ+ state
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Space-variant λ/4 plate
Output: ?
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Transmitted polarization state
Schematic
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Transmitted intensity
Experiment
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Transmitted polarization state
Left-handed elliptical
Right-handed elliptical
Ellipticity <10%
Experiment
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Photo credit: Cayusa, Flickr
Where did the spin
angular momentum
disappear to?
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Cylindrical symmetry means
no angular momentum is
transferred to the plate
Photo credit: pixaio, sxc.hu
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Fascinating!
What does the far field
look like?
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Far field
Angle
Angle
Intensity (arb. units)
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Far field
Angle
Angle
Intensity (arb. units)
No hole in
the middle!
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Far field
Component with the same
handedness as the input (σ+)
Component with opposite
handedness to the input (σ−)
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Phase of central spot
Component with the same
handedness as the input (σ+)
Component with opposite
handedness to the input (σ−)