title: Singular diffraction-free surface plasmon beams generated by overlapping phase-shifted sources.
abstract: We propose and experimentally demonstrate the singular surface plasmon beam that presents a dark channel generated by a point dislocation and a long diffraction-free propagation distance up to 70λ(sp). The singular surface beam is the result of the interference of two surface plasmon polariton (SPP) plane waves, which are launched by two coupling gratings with lateral displacement. An aperture-type near-field scanning optical microscope is used to map the intensity distribution of the singular SPP waves. The propagating point dislocation embedded in the beam is shown by full-wave calculations and is later verified by near-field interference in the experiment.
authors.affiliation: Institute of Modern Optics, Key Laboratory of Optical Information Science & Technology, Ministry of Education of China, Nankai University, Tianjin, China.
authors.forename: Shibiao
authors.initials: S
authors.lastname: Wei
authors.forename: Jiao
authors.initials: J
authors.lastname: Lin
authors.forename: Qian
authors.initials: Q
authors.lastname: Wang
authors.forename: Guanghui
authors.initials: G
authors.lastname: Yuan
authors.forename: Luping
authors.initials: L
authors.lastname: Du
authors.forename: Rong
authors.initials: R
authors.lastname: Wang
authors.forename: Le
authors.initials: L
authors.lastname: Xu
authors.forename: Minghui
authors.initials: M
authors.lastname: Hong
authors.forename: Changjun
authors.initials: C
authors.lastname: Min
authors.forename: Xiaocong
authors.initials: X
authors.lastname: Yuan