title: Giant optical activity in quasi-two-dimensional planar nanostructures.
abstract: We examine the spectral dependence in the visible frequency range of the polarization rotation of two-dimensional gratings consisting of chiral gold nanostructures with subwavelength features. The gratings, which do not diffract, are shown to exhibit giant specific rotation (approximately 10(4) degrees/mm) of polarization in direct transmission at normal incidence. The rotation is the same for light incident on the front and back sides of the sample. Such reciprocity indicates three dimensionality of the structure arising from the asymmetry of light-plasmon coupling at the air-metal and substrate-metal interfaces. The structures thus enable polarization control with quasi-two-dimensional planar objects. However, in contradiction with recently suggested interpretation of experiments on larger scale but otherwise similar structures, the observed polarization phenomena violate neither reciprocity nor time-reversal symmetry.
authors.affiliation: Department of Applied Physics, University of Tokyo, and Solution Oriented Research for Science and Technology, JST, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan.
authors.forename: Makoto
authors.initials: M
authors.lastname: Kuwata-Gonokami
authors.forename: Nobuyoshi
authors.initials: N
authors.lastname: Saito
authors.forename: Yusuke
authors.initials: Y
authors.lastname: Ino
authors.forename: Martti
authors.initials: M
authors.lastname: Kauranen
authors.forename: Konstantins
authors.initials: K
authors.lastname: Jefimovs
authors.forename: Tuomas
authors.initials: T
authors.lastname: Vallius
authors.forename: Jari
authors.initials: J
authors.lastname: Turunen
authors.forename: Yuri
authors.initials: Y
authors.lastname: Svirko