title: Phase singularity of surface plasmon polaritons generated by optical vortices.
abstract: We demonstrate an experimental result that shows the phase singularity of surface plasmon waves generated by the direct transform of optical vortices at normal incidence focused on a structureless metal surface. The near-field two-dimensional intensity distribution near the focal plane is experimentally examined by using near-field scanning optical microscopy and shows a good agreement with the finite-difference time-domain simulation result. The experimental realization demonstrates a potential of the proposed excitation scheme to be reconfigured locally with advantages over structures milled into optically thick metallic films for plasmonics applications involving plasmonic vortices.
authors.affiliation: School of Electrical & Electronic Engineering, Nanyang Technological University, Nanyang Avenue, 639798. Singapore.
authors.forename: P S
authors.initials: PS
authors.lastname: Tan
authors.forename: G H
authors.initials: GH
authors.lastname: Yuan
authors.forename: Q
authors.initials: Q
authors.lastname: Wang
authors.forename: N
authors.initials: N
authors.lastname: Zhang
authors.forename: D H
authors.initials: DH
authors.lastname: Zhang
authors.forename: X-C
authors.initials: XC
authors.lastname: Yuan