title: Broadband nonreciprocal quadrupolarization-induced asymmetric transmission (Q-AT) in plasmonic nanoparticle aggregates.
abstract: Non-reciprocal asymmetric transmission, i.e., the dependence of optical transmittance on the direction of light propagation in the material, can be used in optical isolators or photonic circuits. Broadband asymmetric transmission is observed in near-field coupled aggregates of small plasmonic nanoparticles, even for unpolarized light. Non-reciprocity is demonstrated and, using a phenomenological model, induced electric quadrupole moments are identified as the root cause of the effect.
authors.affiliation: Division of Molecular Imaging and Photonics, Department of Chemistry, KU Leuven, Celestijnenlaan 200D, Box 2425, 3001, Heverlee, Leuven, Belgium.
authors.forename: Ward
authors.initials: W
authors.lastname: Brullot
authors.forename: Tom
authors.initials: T
authors.lastname: Swusten
authors.forename: Thierry
authors.initials: T
authors.lastname: Verbiest
keywords: asymmetric transmission; electric quadrupoles; nanoparticle aggregates; near-field plasmon coupling; nonreciprocal