title: Contribution of double scattering to structural coloration in quasiordered nanostructures of bird feathers.
abstract: We measured the polarization- and angle-resolved optical scattering and reflection spectra of the quasiordered nanostructures in the bird feather barbs. In addition to the primary peak that originates from single scattering, we observed a secondary peak which exhibits depolarization and distinct angular dispersion. We explained the secondary peak in terms of double scattering, i.e., light is scattered successively twice by the structure. The two sequential single-scattering events are considered uncorrelated. Using the Fourier power spectra of the nanostructures obtained from the small-angle x-ray scattering experiment, we calculated the double scattering of light in various directions. The double-scattering spectrum is broader than the single-scattering spectrum, and it splits into two subpeaks at larger scattering angle. The good agreement between the simulation results and the experimental data confirms that double scattering of light makes a significant contribution to the structural color.
authors.affiliation: Department of Applied Physics, Yale University, New Haven, Connecticut 06511, USA.
authors.forename: Heeso
authors.initials: H
authors.lastname: Noh
authors.forename: Seng Fatt
authors.initials: SF
authors.lastname: Liew
authors.forename: Vinodkumar
authors.initials: V
authors.lastname: Saranathan
authors.forename: Richard O
authors.initials: RO
authors.lastname: Prum
authors.forename: Simon G J
authors.initials: SG
authors.lastname: Mochrie
authors.forename: Eric R
authors.initials: ER
authors.lastname: Dufresne
authors.forename: Hui
authors.initials: H
authors.lastname: Cao
mesh_terms: D000818:Animals; D001703:Biophysics / Q000379:methods*; D001717:Birds; D005241:Feathers / Q000502:physiology*; D005583:Fourier Analysis; D008027:Light; D049329:Nanostructures / Q000737:chemistry*; D036103:Nanotechnology / Q000379:methods; D055095:Optics and Photonics; D012542:Scattering, Radiation; D014965:X-Rays; D053800:beta-Keratins / Q000737:chemistry
chemical_list: D053800:beta-Keratins