Mapping electromagnetic fields near a subwavelength hole
D. V. Permyakov+, I. S. Mukhin+*, I. I. Shishkin+, A. K. Samusev+, P. A. Belov+, Yu. S. Kivshar+×
+ITMO University, 197101 St. Petersburg, Russia
*St. Petersburg Academic University of the RAS, 194021 St. Petersburg, Russia
×Nonlinear Physics Center, Research School of Physics and Engineering, Australian National University,
ACT 0200 Canberra, Australia
Abstract
We study, both experimentally and theoretically, the scattering of
electromagnetic waves by a subwavelength hole fabricated in a thin metallic
film. We employ the scanning near-field optical microscopy in order to
reconstruct experimentally the full three-dimensional structure of the
electromagnetic fields in the vicinity of the hole. We observe an
interference of all excited waves with an incident laser beam which allows us
to gain the information about the wave phases. Along with the well-known
surface plasmon polaritons propagating primarily in the direction of the
incident beam polarization, we observe the free-space radiation diffracted by
the hole. We compare the experimental results with the fields of pure
electric and pure magnetic dipoles as well as with direct numerical
simulations. We confirm that a single hole in a thin metallic film excited at
the normal incidence manifests itself as an effective magnetic dipole in the
visible spectral range.