title: Observation and modeling of polarized light from scarab beetles.
abstract: The light reflected from scarab beetles illuminated with unpolarized white light is analyzed ellipsometrically and displayed as the sum of an elliptically polarized spectrum I(p) and an unpolarized spectrum I(u). A chirped stack of chiral resonators, each with a characteristic Bragg wavelength and partial realignment of birefringent material to a fixed axis, is proposed as a model for simulation of both reflection and polarization spectra. Possible mechanisms that effectively eliminate impedance mismatch at the air-elytron interface and allow some beetles to exhibit nearly perfect circularly polarized reflections are discussed. Results are presented for three representative beetles, Ischiosopha bifasciata, which is shown to be a narrowband left-circular polarizer; Chrysophora chrysochlora, a broadband left-circular polarizer; and Chrysina woodi, an elliptical polarizer. The methods that are developed are applicable to the more general problem of synthesis of reflectors with prescribed reflection and polarization spectra.
authors.affiliation: Department of Physics, University of Otago, Dunedin, New Zealand.
authors.forename: Sam
authors.initials: S
authors.lastname: Lowrey
authors.forename: Lakshman
authors.initials: L
authors.lastname: De Silva
authors.forename: Ian
authors.initials: I
authors.lastname: Hodgkinson
authors.forename: John
authors.initials: J
authors.lastname: Leader
mesh_terms: D000465:Algorithms; D000818:Animals; D001517:Coleoptera; D008027:Light; D008954:Models, Biological; D010775:Photic Stimulation / Q000295:instrumentation* / Q000379:methods*