Polarization-Selective Coupling to Long-Range Surface Plasmon Polariton Waveguides

We demonstrate polarization-selective coupling from an optical fiber to long-range surface plasmon polariton waveguide modes using plasmonic antenna arrays. The arrays allow the sorting of two distinct (not necessarily orthogonal) polarizations to counter-propagating waveguide modes. The polarization-selective behavior of the devices is described by a compact formalism based on Stokes vectors that offers a clear graphical representation of the response. We experimentally observe polarization-controlled switching and unidirectional coupling with extinction ratios greater than 30 dB and coupling efficiencies comparable to those of a conventional grating coupler.