Spin-Hall effect in the scattering of structured light from plasmonic nanowire

Abstract

Spin-orbit interactions are subwavelength phenomena that can potentially lead to numerous device-related applications in nanophotonics. Here, we report the spin-Hall effect in the forward scattering of Hermite-Gaussian (HG) and Gaussian beams from a plasmonic nanowire. Asymmetric scattered radiation distribution was observed for circularly polarized beams. Asymmetry in the scattered radiation distribution changes the sign when the polarization handedness inverts. We found a significant enhancement in the spin-Hall effect for a HG beam compared to a Gaussian beam for constant input power. The difference between scattered powers perpendicular to the long axis of the plasmonic nanowire was used to quantify the enhancement. In addition, the nodal line of the HG beam acts as the marker for the spin-Hall shift. Numerical calculations corroborate experimental observations and suggest that the spin flow component of the Poynting vector associated with the circular polarization is responsible for the spin-Hall effect and its enhancement.

Simultaneous detection of spin and orbital angular momentum of light through scattering from a single silver nanowire

“…32,33 The uniform morphology renders them useful for low loss surface plasmon waveguiding property 34 and makes them ideal for fundamental photonic circuit applications such as plasmonic waveguide, 34,35 plasmonic antenna, 36,37 logic gates 38 as well as for optoelectrical applications. 39 Additionally, in our previous reports we have shown how an AgNW can act as a plasmonic scatterer in sensing total energy flow of an incident beam 40,41 and as well as probing the inherent spin-Hall effect. 42 In this work, a single AgNW dropcasted on a glass substrate has been used as a nanoscopic strip diffractor and the scattered pattern has been extensively analyzed to ascertain the spin and orbital angular momentum state of the incident light, as shown in Figure 1.…”

“…The focal optical field and its orbital and spin flow constituents, upon interaction with a nano structure will lead to flow dependant scattering allowing us to determine its state. Although different nano-structures have been shown to have exhibited orbital flow dependant scattering, 29,30,40,41,46 differential sensing of spin and orbital flow is yet to be achieved by a single nano-object. To that end, we use a single crystalline silver nanowire (AgNW) to scatter the incident optical field and sense its properties.…”

Optical Spin Hall Effect in Closed Elliptical Plasmonic Nanoslit with Noncircular Symmetry

“…The optical spin Hall effect (OSHE), a phenomenon originally demonstrated by the spin-dependent transverse shifts of light reflected or refracted by a plane interface, has attracted enormous interest and evoked many pioneering studies [1][2][3][4][5][6] since it was proposed by Onoda as an analogy to the electron spin Hall effect [7]. Inherently, the OSHE is a manifestation of the geometric phase in light propagation [8,9], which is originated from the spin-orbit interactions (SOIs) of light [1,3] and has provided a novel route for the spin-dependent manipulation of light field, such as generalized refraction [1], holography with metasurfaces [10][11][12], and creation of specific beams or fields [13][14][15][16].…”

Experimental observation of transverse spin of plasmon polaritons in a single-crystalline silver nanowire

“…45,46 In all of these cases transverse spin can play an important role in modifying the phenomena and add to a more complete description of the resultant effects such as directional coupling, 47,48 spin-hall effect. 19,49 Motivated by this, herein we study transverse spin of SPP field excited in a quasi-onedimensional AgNW placed on a glass substrate as shown in Fig. 1.…”