Open AccessFinite-difference time-domain (FDTD) analysis on the interaction between a metal block and a radially polarized focused beam
Author(s) -
Kyoko Kitamura,
Kyosuke Sakai,
Susumu Noda
Publication year - 2011
Publication title -
optics express
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.394
H-Index - 271
ISSN - 1094-4087
DOI - 10.1364/oe.19.013750
Subject(s) - poynting vector , finite difference time domain method , optics , physics , electric field , beam (structure) , field (mathematics) , quantum mechanics , mathematics , magnetic field , pure mathematics
Radially polarized focused beams have attracted a great deal of attention because of their unique properties characterized by the longitudinal field. Although this longitudinal field is strongly confined to the beam axis, the energy flow, i.e., the Poynting vector, has null intensity on the axis. Hence, the interaction of the focused beam and matter has thus far been unclear. We analyzed the interactions between the focused beam and a subwavelength metal block placed at the center of the focus using three-dimensional finite-difference time-domain (FDTD) calculation. We found that most of the Poynting energy propagates through to the far-field, and that a strong enhancement of the electric field appeared on the metal surface. This enhancement is attributed to the constructive interference of the symmetric electric field and the coupling to the surface plasmon mode.