title: Nanostructured potential of optical trapping using a plasmonic nanoblock pair.
abstract: We performed two-dimensional mapping of optical trapping potentials experienced by a 100 nm dielectric particle above a plasmon-resonant gold nanoblock pair with a gap of several nanometers. Our results demonstrate that the potentials have nanoscale spatial structures that reflect the near-field landscape of the nanoblock pair. When an incident polarization parallel to the pair axis is rotated by 90°, a single potential well turns into multiple potential wells separated by a distance smaller than the diffraction limit; this is associated with super-resolution optical trapping. In addition, we show that the trap stiffness can be enhanced by approximately 3 orders of magnitude compared to that with conventional far-field trapping.
authors.affiliation: Research Institute for Electronic Science, Hokkaido University, Sapporo 001-0020, Japan.
authors.forename: Yoshito
authors.initials: Y
authors.lastname: Tanaka
authors.forename: Shogo
authors.initials: S
authors.lastname: Kaneda
authors.forename: Keiji
authors.initials: K
authors.lastname: Sasaki