title: Absence of red structural color in photonic glasses, bird feathers, and certain beetles.
abstract: Colloidal glasses, bird feathers, and beetle scales can all show structural colors arising from short-ranged spatial correlations between scattering centers. Unlike the structural colors arising from Bragg diffraction in ordered materials like opals, the colors of these photonic glasses are independent of orientation, owing to their disordered, isotropic microstructures. However, there are few examples of photonic glasses with angle-independent red colors in nature, and colloidal glasses with particle sizes chosen to yield structural colors in the red show weak color saturation. Using scattering theory, we show that the absence of angle-independent red color can be explained by the tendency of individual particles to backscatter light more strongly in the blue. We discuss how the backscattering resonances of individual particles arise from cavity-like modes and how they interact with the structural resonances to prevent red. Finally, we use the model to develop design rules for colloidal glasses with red, angle-independent structural colors.
authors.affiliation: Department of Physics, Harvard University, 17 Oxford Street, Cambridge, Massachusetts 02138.
authors.forename: Sofia
authors.initials: S
authors.lastname: Magkiriadou
authors.affiliation: School of Engineering and Applied Sciences, Harvard University, 29 Oxford Street, Cambridge, Massachusetts 02138.
authors.forename: Jin-Gyu
authors.initials: JG
authors.lastname: Park
authors.affiliation: Korea Electronics Technology Institute, Bundang-gu, Seongnam-Si, Gyeonggi-do, Korea.
authors.forename: Young-Seok
authors.initials: YS
authors.lastname: Kim
authors.affiliation: Department of Physics, Harvard University, 17 Oxford Street, Cambridge, Massachusetts 02138 and School of Engineering and Applied Sciences, Harvard University, 29 Oxford Street, Cambridge, Massachusetts 02138.
authors.forename: Vinothan N
authors.initials: VN
authors.lastname: Manoharan
mesh_terms: D000818:Animals; D032701:Biomimetics; D001717:Birds; D001517:Coleoptera; D003116:Color; D005241:Feathers; D005898:Glass; D055620:Optical Phenomena; D017785:Photons; D010858:Pigmentation; D019904:Polymethyl Methacrylate
chemical_list: D019904:Polymethyl Methacrylate