Three-dimensional orientation-unlimited polarization encryption by a single optically configured vectorial beam.

The interplay between light polarization and matter is the basis of many fundamental physical processes and applications. However, the electromagnetic wave nature of light in free space sets a fundamental limit on the three-dimensional polarization orientation of a light beam. Although a high numerical aperture objective can be used to bend the wavefront of a radially polarized beam to generate the longitudinal polarization state in the focal volume, the arbitrary three-dimensional polarization orientation of a beam has not been achieved yet.

Plasmonic rainbow rings induced by white radial polarization.

This Letter presents a scheme to embed both angular/spectral surface plasmon resonance (SPR) in a unique far-field rainbow feature by tightly focusing (effective NA=1.45) a polychromatic radially polarized beam on an Au (20 nm)/SiO2 (500 nm)/Au (20 nm) sandwich structure. Without the need for angular or spectral scanning, the virtual spectral probe snapshots a wide operation range (n=1-1.

Manipulation of the steering and shaping of SPPs via spatially inhomogeneous polarized illumination.

In this paper, we demonstrated a far-field scheme for the manipulation of locally excited surface plasmon polaritons (SPPs). This scheme features steering and shaping capabilities, and relies on the focusing of a high numerical aperture, in conjunction with spatially inhomogeneous polarized (SIP) illumination. We were able to control the propagation and direction of SPPs, via the field distribution of polarization at the entrance pupil, without the need for an aperture, protrusion or any other near-field features.