Observation of the Geometric Spin Hall Effect of Light

Applied Physics B, 2011

The geometric Spin Hall Effect of Light (geometric SHEL) amounts to a polarization-dependent positional shift when a light beam is observed from a reference frame tilted with respect to its direction of propagation. Motivated by this intriguing phenomenon, the energy density of the light beam is decomposed into its Cartesian components in the tilted reference frame. This illustrates the occurrence of the characteristic shift and the significance of the effective response function of the detector.

Physical Review A, 2014

Recently, it was shown that a nonzero transverse angular momentum manifests itself in a polarization-dependent intensity shift of the barycenter of a paraxial light beam [Aiello et al., Phys. Rev. Lett. 103, 100401 (2009)]. The underlying effect is phenomenologically similar to the spin Hall effect of light but does not depend on the specific light-matter interaction and can be interpreted as a purely geometric effect. Thus, it was named the geometric spin Hall effect of light. Here, we experimentally investigate the appearance of this effect in tightly focused vector beams. We use an experimental nanoprobing technique in combination with a reconstruction algorithm to verify the relative shifts of the components of the electric energy density and the shift of the intensity in the focal plane. By that, we experimentally demonstrate the geometric spin Hall effect of light in a highly nonparaxial beam.

We describe a novel phenomenon occurring when a polarized Gaussian beam of light is observed in a Cartesian reference frame whose axes are not parallel to the direction of propagation of the beam. Such phenomenon amounts to an intriguing spin-dependent shift of the position of the center of the beam, with manners akin to the spin Hall effect of light. We demonstrate that this effect is unavoidable when the light beam possesses a nonzero transverse angular momentum.

Physical Review Letters, 2009

Electromagnetic waves carry angular momenta, and, due to spin-orbit interaction, an encounter with a gradient of refractive index leads to transport of spin similar to the electronic spin Hall effect. We show here that transversal spin transport is possible even when the symmetry of optical interaction is of higher dimensionality. We demonstrate that for a wave in a pure state of polarization, the spin-orbit interaction results in a spiraling power flow that is determined by the extent of the interaction. As a result, the spin transport can be resonantly enhanced in a spherical geometry. Our results open the possibility for developing new functionalities for photonic devices.

Optics letters, 2013

We demonstrate a experimental method to measure the spin Hall effect of light (SHEL), which is based on the interference between two orthogonal circularly polarized beams with the help of a polarizer. Our method can measure the SHEL across the entire exit pupil, not only at the centroid as is the case with earlier methods, and hence one can scan the transverse section of the beam. We measured the SHEL of an aluminium mirror and a glass plate using a He-Ne laser at wavelength 633 nm, for incidence angles varying from 22° to 70°. The experimental results are in good agreement with theory. We also measured the shift across the transverse section of a Gaussian beam using same method.

Physical Review A, 2019

By analyzing the vectorial Helmholtz equation within the thin-layer approach, we find that light acquires a novel geometrical phase, in addition to the usual one (the optical Berry phase), during the propagation along a curved path. Unlike the optical Berry phase, the novel geometrical phase is induced by the transverse spin along the binormal direction and associated with the curvature of the curve. Furthermore, we show a novel Hall effect of light induced by the torsion of the curve and associated with the transverse spin along the binormal direction, which is different from the usual spin Hall effect of light. Finally, we demonstrate that the usual and novel geometrical phase phenomena are described by different geometry-induced U(1) gauge fields in different adiabatic approximations. In the nonadiabatic case, these gauge fields are united in one effective equation by SO(3) group.

Physical Review Letters, 2009

We present a novel fundamental phenomenon occurring when a polarized beam of light is observed from a reference frame tilted with respect to the direction of propagation of the beam. This effect has a purely geometric nature and amounts to a polarization-dependent shift or split of the beam intensity distribution evaluated as the time-averaged flux of the Poynting vector across the plane of observation. We demonstrate that such a shift is unavoidable whenever the beam possesses a nonzero transverse angular momentum. This latter result has general validity and applies to arbitrary systems such as, e.g., electronic and atomic beams.

Physical Review Letters, 2005

A remarkable analogy is established between the well-known spin Hall effect and the polarization dependence of Rayleigh scattering of light in microcavities. This dependence results from the strong spin effect in elastic scattering of exciton polaritons: if the initial polariton state has a zero spin and is characterized by some linear polarization, the scattered polaritons become strongly spin polarized. The polarization in the scattered state can be positive or negative dependent on the orientation of the linear polarization of the initial state and on the direction of scattering. Very surprisingly, spin polarizations of the polaritons scattered clockwise and anticlockwise have different signs. The optical spin Hall effect is possible due to strong longitudinal-transverse splitting and finite lifetime of exciton polaritons in microcavities.

In an oblique section of a paraxial beam with angular momentum, the beam center of gravity (CG) is shifted with respect to its position in the normal cross section. We relate this shift with the internal energy redistribution occurring on the passage between the normal and oblique sections. The transverse orbital flow explains the effect for scalar beams, similar incorporation of the spin flow enables explanation of the CG shift in oblique sections of the elliptically polarized beams. Role of the special properties of the positionsensitive detector placed in the oblique beam section is discussed.

Applied Physics Letters, 2017

The optical spin Hall effect is a transport phenomenon of exciton polaritons in semiconductor microcavities, caused by the polaritonic spin-orbit interaction, which leads to the formation of spin textures. The control of the optical spin Hall effect via light injection in a double microcavity is demonstrated. Angular rotations of the polarization pattern up to 22 are observed and compared to a simple theoretical model. The device geometry is responsible for the existence of two polariton branches which allows a robust independent control of the polariton spin and hence the polarization state of the emitted light field, a solution technologically relevant for future spin-optronic devices.