Polarization of light and topological phases

Generating optical orbital angular momentum at visible wavelengths using a plasmonic metasurface

“…Thus, such a physical rotation introduces a global phase proportional to half of the solid angle enclosed by the polarisation trajectories (pole-to-pole) on the polarisation Poincaré sphere. 5 This global phase is equal to j2hj, where h describes the angle over which the array has rotated. Next, we consider the particular case of a cylindrically symmetric metasurface possessing a transverse topological charge q51-meaning the nano-antenna orientation performs one full rotation along a path surrounding the origin.…”

“…This relationship can be described by the Pancharatnam-Berry (geometrical) phase, 4 and is what allows a beam to experience different optical paths associated with the trajectory of the polarisation evolution on the Poincaré sphere. 5 Recently, this phenomenon has enabled PancharatnamBerry phase optical elements: 6,7 devices that control the output beam's wavefront according to the polarisation of the input beam. These devices could easily be inserted into the beam path of existing spectroscopic, nano-imaging or communication systems, as they do not rely on diffraction, adding OAM-based functionality that has the potential to distinguish between molecules of different chirality, enhance optical circular dichroism 8 and encode multiple bits of information onto a single photon.…”

Dynamics of defects in the vector complex Ginzburg–Landau equation

“…Thus the description of the dynamics is done in terms of a scalar field. However in the cases in which the polarization of the light is not fixed, the vector nature of the electromagnetic field leads to striking topological phenomena [3]. Recently reported examples of localized structures for which the polarization plays a fundamental role include points of zero amplitude in both components of the field in a periodic elliptically polarized background, found in type II OPO [4] and dots of low amplitude in a circularly polarized component of the field in an almost circularly polarized background found in self-defocusing vectorial Kerr resonators [5].…”

Optical Spin-to-Orbital Angular Momentum Conversion in Inhomogeneous Anisotropic Media

“…This principle is actually not limited to the generation of helical waves, but it can be extended to any wavefront shaping controlled by polarization transformations, thus setting the basis for an entirely new approach to the design of phase optical elements [24,25], an approach of which our work represents the first actual demonstration in the 6 visible domain.…”