title: Diffraction limited focusing and routing of gap plasmons by a metal-dielectric-metal lens.
abstract: Passive optical elements can play key roles in photonic applications such as plasmonic integrated circuits. Here we experimentally demonstrate passive gap-plasmon focusing and routing in two-dimensions. This is accomplished using a high numerical-aperture metal-dielectric-metal lens incorporated into a planar-waveguide device. Fabrication via metal sputtering, oxide deposition, electron- and focused-ion- beam lithography, and argon ion-milling is reported on in detail. Diffraction-limited focusing is optically characterized by sampling out-coupled light with a microscope. The measured focal distance and full-width-half-maximum spot size agree well with the calculated lens performance. The surface plasmon polariton propagation length is measured by sampling light from multiple out-coupler slits.
authors.forename: Brian S
authors.initials: BS
authors.lastname: Dennis
authors.forename: David A
authors.initials: DA
authors.lastname: Czaplewski
authors.forename: Michael I
authors.initials: MI
authors.lastname: Haftel
authors.forename: Daniel
authors.initials: D
authors.lastname: Lopez
authors.forename: Girsh
authors.initials: G
authors.lastname: Blumberg
authors.forename: Vladimir
authors.initials: V
authors.lastname: Aksyuk