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E. Hasman and V. Kleiner
[6, 7], enhanced coherent thermal emission [8, 9], surface-enhanced Raman scattering [10], planar optical chirality [11, 12] and super-resolution [13, 14]. Apparently,
the handedness of the light’s polarization (optical spin up/down) may provide an additional degree of freedom in nanoscale photonics. The dynamics of spinning light was
recently investigated, and the effect of spin on the trajectories of polarized light beams
(spin-orbit coupling) was experimentally observed [15], with results that agree with
the predictions of Berry’s phase theory. In this chapter we examine the spin-orbit
coupling effects that appear when a wave carrying intrinsic angular momentum (spin)
interacts with a nanoscale structures which support SPP. The Berry’s phase is shown
to be a manifestation of the Coriolis effect in noninertial reference frame attached to
the wave. A variety of experiments demonstrate spin-dependent effects in the electromagnetic waves coupling via an anisotropic inhomogeneous nanostructure. In the
Sect. 13.2 we present and discuss the observation of spin-dependent surface-plasmon
phenomena in anisotropic nanostructures on metal surface. In the Sect. 13.3 we consider plasmonic nanoapertures which exhibit a crucial role of an angular momentum
(AM) selection rule in a light-surface plasmon scattering process, which is accompanied by a spin symmetry breaking effect due to spin-orbit interaction. Section 13.4 is
devoted to properties of plasmonic nanoapertures which demonstrate behavior that is
analogous to the Aharonov-Bohm effect. In Sect. 13.5 properties of the nanoapertures
as topological defects are considered in relation with potential spinoptical devices
having a spiral point spread function. An optical spin Hall effect in this system due to
spin-orbit coupling which can be observed in the far-field is then studied in detail in
Sect. 13.6. In the final Sect. 13.7 observation of an optical Rashba effect—spin degeneracy breaking due to spin-orbit interaction—in thermal radiation emitted from an
inhomogeneous anisotropic 2D lattice composed of coupled antennas is presented.
The spin split dispersion arises from the inversion symmetry violation in the lattice.
13.2 Spin-Based Plasmonic Effect in Nanoscale Structures
In this section we will describe a spin-dependent behavior of SPPs that was
experimentally found in the interaction of light with metallic anisotropic and
inhomogeneous nanoscale structures [16]. The anisotropic plasmonic structure under
consideration is produced on top of a thin metal film evaporated onto a glass plate
(Fig. 13.1a, b). The element consists of a spiral Bragg grating with a central defect,
surrounded by a coupling grating, both of which were etched to a depth of 50 nm by a
focused ion beam (FIB). The thickness of the metal (Au) was chosen to be 100 nm in
order to prevent any direct transmission of light. The grating provides coupling with
normally incident light at ε 0 = 532 nm to a surface-plasmon wave, while the Bragg
grating with a central defect serves as a plasmonic microcavity for the surface wave.
Therefore, the actual coupler period and the Bragg period were chosen to be 0.5 and
0.25 µm, respectively. The outer diameter of the structure of 10 µm and the small
radius of the spiral cavity r 0 = 1.32 µm are consistent with the surface plasmon propagation length [17] L c ∪ 1/Im
k p
, which is about 3 µm for gold at this wavelength.
E. Hasman and V. Kleiner
[6, 7], enhanced coherent thermal emission [8, 9], surface-enhanced Raman scattering [10], planar optical chirality [11, 12] and super-resolution [13, 14]. Apparently,
the handedness of the light’s polarization (optical spin up/down) may provide an additional degree of freedom in nanoscale photonics. The dynamics of spinning light was
recently investigated, and the effect of spin on the trajectories of polarized light beams
(spin-orbit coupling) was experimentally observed [15], with results that agree with
the predictions of Berry’s phase theory. In this chapter we examine the spin-orbit
coupling effects that appear when a wave carrying intrinsic angular momentum (spin)
interacts with a nanoscale structures which support SPP. The Berry’s phase is shown
to be a manifestation of the Coriolis effect in noninertial reference frame attached to
the wave. A variety of experiments demonstrate spin-dependent effects in the electromagnetic waves coupling via an anisotropic inhomogeneous nanostructure. In the
Sect. 13.2 we present and discuss the observation of spin-dependent surface-plasmon
phenomena in anisotropic nanostructures on metal surface. In the Sect. 13.3 we consider plasmonic nanoapertures which exhibit a crucial role of an angular momentum
(AM) selection rule in a light-surface plasmon scattering process, which is accompanied by a spin symmetry breaking effect due to spin-orbit interaction. Section 13.4 is
devoted to properties of plasmonic nanoapertures which demonstrate behavior that is
analogous to the Aharonov-Bohm effect. In Sect. 13.5 properties of the nanoapertures
as topological defects are considered in relation with potential spinoptical devices
having a spiral point spread function. An optical spin Hall effect in this system due to
spin-orbit coupling which can be observed in the far-field is then studied in detail in
Sect. 13.6. In the final Sect. 13.7 observation of an optical Rashba effect—spin degeneracy breaking due to spin-orbit interaction—in thermal radiation emitted from an
inhomogeneous anisotropic 2D lattice composed of coupled antennas is presented.
The spin split dispersion arises from the inversion symmetry violation in the lattice.
13.2 Spin-Based Plasmonic Effect in Nanoscale Structures
In this section we will describe a spin-dependent behavior of SPPs that was
experimentally found in the interaction of light with metallic anisotropic and
inhomogeneous nanoscale structures [16]. The anisotropic plasmonic structure under
consideration is produced on top of a thin metal film evaporated onto a glass plate
(Fig. 13.1a, b). The element consists of a spiral Bragg grating with a central defect,
surrounded by a coupling grating, both of which were etched to a depth of 50 nm by a
focused ion beam (FIB). The thickness of the metal (Au) was chosen to be 100 nm in
order to prevent any direct transmission of light. The grating provides coupling with
normally incident light at ε 0 = 532 nm to a surface-plasmon wave, while the Bragg
grating with a central defect serves as a plasmonic microcavity for the surface wave.
Therefore, the actual coupler period and the Bragg period were chosen to be 0.5 and
0.25 µm, respectively. The outer diameter of the structure of 10 µm and the small
radius of the spiral cavity r 0 = 1.32 µm are consistent with the surface plasmon propagation length [17] L c ∪ 1/Im
k p
, which is about 3 µm for gold at this wavelength.