AVS 46th International Symposium
    Thin Films Division Thursday Sessions
       Session TF-ThM

Paper TF-ThM8
Optical Properties of Chiral Thin Film Nanostructures and Composites

Thursday, October 28, 1999, 10:40 am, Room 615

Session: Nanophase Thin Films
Presenter: S.R. Kennedy, University of Alberta, Canada
Authors: S.R. Kennedy, University of Alberta, Canada
J.C. Sit, University of Alberta, Canada
M.J. Brett, University of Alberta, Canada
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We have fabricated porous, chiral thin films with distinct helical nanostrucutures of dimension 300nm pitch and 100nm separation. The geometry of these microstructures can be easily controlled by careful substrate motion using the GLancing Angle Deposition (GLAD) technique.@footnote 1@ Because of their nanometer size scale, these helices give rise to optical phenomena, such as the wavelength specific rotation of linearly polarized light, or optical activity. Analysis of films has found that optical properties are functions of film material and thickness as well as helical pitch and radius. All of these characteristics can be accurately controlled during the deposition process to tailor the film's properties to the desired wavelength regime and rotatory power. For example, we have measured a peak rotation of 2.0° at a wavelength of 480nm when polarized light is incident normal to the plane of the film. The porosity of GLAD thin films has also allowed us to fill gaps surrounding the nano-helices with fluids to enhance the film properties. By filling the films with substances of varying indices of refraction, we were able to modify the rotational effect. In addition to filling with non-active fluids, we investigated the effect of combining optically active nematic liquid crystals with our chiral films. @FootnoteText@ @footnote 1@Robbie, K., & Brett, M. J., Nature, v13, 616 (1996).