Structural and optical properties of chiral natural photonic structures determined from spectroscopic Mueller-matrix data
2012 (English)In: E-MRS 2012 Fall Meeting, 2012Conference paper, Abstract (Other academic)
Resume : In nature one can find advanced photonic structures which often are multifunctional. High-precision analysis of such structures is a prerequisite for a biomimetic approach to synthesize analogous structures for technical applications. Here we employ spectroscopic Mueller-matrix ellipsometry to address chiral photonic structures in scarab beetles. Such structures exhibit structural colors with metallic shine but also complex polarization properties. At the same time they are hard and lightweight components in the exoskeleton of beetles. With a dual rotating compensator ellipsometer we measure Mueller-matrix data on beetles with precision better than ±0.005 in the range 350 – 1000 nm at angles of incidence 20-75º. These Mueller matrices directly provide phenomenological descriptions of polarization properties of exoskeletons and both left-handed and right-handed near-circularly reflected light can be found. By using non-linear regression analysis with Mueller-matrix data and an appropriate structural model, one can extract structural and optical details including pitch of the helical structure, as well as thicknesses and the refractive indices of the various layers in the birefringent chitin-based materials constituting the exoskeleton. The applications of Mueller-matrix analysis will be demonstrated on a selection of photonic structures in scarab beetles including wide band non-chiral, narrow-band chiral and wide-band chiral structures.
Place, publisher, year, edition, pages
IdentifiersURN: urn:nbn:se:liu:diva-86509OAI: oai:DiVA.org:liu-86509DiVA: diva2:578331
E-MRS 2012 Fall Meeting, 17-21 September, 2012, Warsaw
ProjectsNatural Photonic Nanostructures
FunderSwedish Research Council, 621-2011-4283Knut and Alice Wallenberg Foundation