Polarization-Controlled Tunable Directional Coupling of Surface Plasmon Polaritons

Abstract

Light can be coupled into propagating electromagnetic surface waves at a metal-dielectric interface known as surface plasmon polaritons (SPPs). This process has traditionally faced challenges in the polarization sensitivity of the coupling efficiency and in controlling the directionality of the SPPs. We designed and demonstrated plasmonic couplers that overcome these limits using polarization-sensitive apertures in a gold film. Our devices enable polarization-controlled tunable directional coupling with polarization-invariant total conversion efficiency and preserve the incident polarization information. Both bidirectional and unidirectional launching of SPPs are demonstrated. The design is further applied to circular structures that create radially convergent and divergent SPPs, illustrating that this concept can be extended to a broad range of applications.

Dye-Assisted Gain of Strongly Confined Surface Plasmon Polaritons in Silver Nanowires

“…[1][2][3][4][5] Noble-metal nanostructures present an excellent platform for strongly confined optical waveguides 6-13 because of their ability to support surface plasmon polaritons (SPPs). 14 However, SPP propagation suffers from losses that seriously limit their application potential.…”

Convolution Operations on Coding Metasurface to Reach Flexible and Continuous Controls of Terahertz Beams

“…As 2D artificially engineered structures,1, 2, 3 metasurfaces have attracted great attention in physics and engineering communities owing to a number of unique properties 4, 5, 6, 7, 8, 9, 10, 11, 12. A metasurface is formed by distributing subwavelength resonant particles with different geometries and materials on a 2D surface, and therefore is able to manipulate both amplitudes and phases of electromagnetic (EM) waves, enabling many extraordinary functionalities such as the polarization conversion,,13, 14, 15, 16, 17 perfect absorption,18, 19, 20 and amplitude and phase modulations 21, 22.…”

Spin–orbit coupling in surface plasmon scattering by nanostructures

“…The effect is based on the reciprocity of optical interactions and the peculiar transverse angular momentum specific to surface electromagnetic waves on a metal-dielectric interface. While in the direct photonic SHE (PSHE), the polarization of the incident light controls the direction of the SPP excitation on a surface [2][3][4][5][6][7] , in the reciprocal scenario, in analogy to the spin injection current control in solidstate spintronic devices (inverse SHE) 8 , the direction of the scattered light of a given polarization is determined by the direction of the SPPs impinging at a scatterer.…”

“…In the electronic SHE, electrons with opposite spins undertake different trajectories in a current flow 1 . In optics, photons with opposite spins-left or right circularly polarized (LCP or RCP) light-may propagate in different directions upon interaction with the material environment if spin-orbital coupling is engineered using, for example, metasurfaces [2][3][4] , Berry phase 5 , refractive index gradient 6 or near-field interference 7 .…”