title: Direct observation of plasmonic index ellipsoids on a deep-subwavelength metallic grating.
abstract: We constructed a metallic grating on a deep-subwavelength scale and tested its plasmonic features in visible frequencies. The deep-subwavelength metallic grating effectively acts as an anisotropic homogeneous uniaxial form-birefringent metal, exhibiting different optical responses for polarizations along different optical axes. Therefore, this form-birefringent metal supports anisotropic surface plasmon polaritons that are characterized by directly imaging the generated plasmonic index ellipsoids in reciprocal space. The observed plasmonic index ellipsoids also show a rainbow effect, where different colors are dispersively distributed in reciprocal space.
authors.affiliation: Department of Electrical and Computer Engineering, University of California, San Diego, La Jolla, California 92093, USA. lfeng@caltech.edu
authors.forename: Liang
authors.initials: L
authors.lastname: Feng
authors.forename: Zhaowei
authors.initials: Z
authors.lastname: Liu
authors.forename: Yeshaiahu
authors.initials: Y
authors.lastname: Fainman