Light manipulation principles in biological photonic systems

© 2013 Science Wise Publishing and DE GRUYTER.The science of light and colour manipulation continues to generate interest across a range of disciplines, from mainstream biology, across multiple physicsbased fields, to optical engineering. Furthermore, the study of light production and manipulation is of significant value to a variety of industrial processes and commercial products. Among the several key methods by which colour is produced in the biological world, this review sets out to describe, in some detail, the specifics of the method involving photonics in animal and plant systems; namely, the mechanism commonly referred to as structural colour generation. Not only has this theme been a very rapidly growing area of physics-based interest, but also it is increasingly clear that the biological world is filled with highly evolved structural designs by which light and colour strongly influence behaviours and ecological functions.We acknowledge the financial support of DARPA contract W911NF-10-C-0069 and of AFOSR grant FA9550-10-1-0020. We also wish to thank Caroline Pouya, Helen Ghiradella, Radislav Potyrailo, Roy Sambles, Shuichi Kinoshita and Doekele Stavenga for helpful discussions

Optically-ambidextrous circularly-polarised reflection from the chiral cuticle of the scarab beetle Chrysina resplendens

This is the author accepted manuscript. The final version is available from Royal Society via the DOI in this record.The evolution of structural colour mechanisms in biological systems has given rise to many interesting optical effects in animals and plants. The instance of the scarab beetle Chrysina resplendens is particularly distinctive. Its exoskeleton has a bright, golden appearance and reflects both right-handed and left-handed circularly-polarized light concurrently. The chiral nanostructure responsible for these properties is a helicoid, in which birefringent dielectric planes are assembled with an incremental rotation. This study correlates details of the beetle’s circularly-polarized reflectance spectra directly with physical aspects of its structural morphology. Electron micrography is used to identify and measure the physical dimensions of the key constituent components. These include a chiral multilayer configuration comprising two chirped, lefthanded helicoids that are separated by a birefringent retarder. A scattering matrix technique is used to simulate the system’s optical behaviour in which the roles of each component of the morphological substructure are elucidated by calculation of the fields throughout its depth.This work was supported by AFOSR grant number FA9550-10-1- 0020

Measuring and modelling optical scattering and the colour quality of white pierid butterfly scales

Copyright © 2009 Optical Society of America. This paper was published in Optics Express and is made available as an electronic reprint with the permission of OSA. The paper can be found at the following URL on the OSA website: http://www.opticsinfobase.org/oe/abstract.cfm?URI=oe-17-17-14729 . Systematic or multiple reproduction or distribution to multiple locations via electronic or other means is prohibited and is subject to penalties under law.Colouration in butterfly wings is due to the interaction of light with a covering of scales on both wing surfaces. A combination of nanostructure in the scales, which reflect or scatter light, and absorption from chemical pigments in the scales and wing substrate create the final colour appearance. We compared the wing scale morphology of the pierid butterfly Pieris rapae (Small White) to the reflectance spectra from its wings. Its wing scales contain a dense array of pterin pigment beads. A positive correlation between bead-array density and wing reflectance, at wavelengths where the pigment does not absorb, was identified and characterised. We observed, however, that light scatter from these beads does not account for all of the broadband light scatter observed from the wings. The rest of the scale structure plays an important role in achieving high light scatter. Furthermore, combining the underlying scattering and absorption mechanisms within the butterfly scales enabled us to quantify the optical characteristics of the samples using CIELab colour theory

Gap Waveguide PMC Packaging for Improved Isolation of Circuit Components in High-Frequency Microwave Modules

In this paper, perfect magnetic conductor (PMC)-based packaging technique was used to improve the isolation performance among various microwave circuit components such as high-gain amplifier chains. In this approach, a periodic structure (such as metal pin rows) together with the ground plane of the substrate created a stopband for unwanted parallel plate or cavity modes as well as substrate modes, and thereby suppressed the problems of circuit resonances and related package phenomena. This paper describes two Ka-band amplifier chains that were tested with this new packaging technique. Firstly, a single amplifier chain was tested for maximum stable gain operation, and it was found that the stable gain of >65 dB was achieved, whereas traditional metal wall package with RF absorber offered stable gain of 40 dB, thus showing significant isolation improvement. Secondly, two high-gain amplifier chains were placed side by side and their mutual isolation was tested. With the proposed gap waveguide packaging, a minimum isolation of 78 dB was achieved, whereas a complete metal shield provided a minimum isolation of only 64 dB over the band of interest

Circularly polarized reflection from the scarab beetle Chalcothea smaragdina: light scattering by a dual photonic structure

Helicoidal architectures comprising various polysaccharides, such as chitin and cellulose, have been reported in biological systems. In some cases, these architectures exhibit stunning optical properties analogous to ordered cholesteric liquid crystal phases. In this work, we characterize the circularly polarized reflectance and optical scattering from the cuticle of the beetle Chalcothea smaragdina (Coleoptera: Scarabaeidae: Cetoniinae) using optical experiments, simulations and structural analysis. The selective reflection of left-handed circularly polarized light is attributed to a Bouligand-type helicoidal morphology within the beetle's exocuticle. Using electron microscopy to inform electromagnetic simulations of this anisotropic stratified medium, the inextricable connection between the colour appearance of C. smaragdina and the periodicity of its helicoidal rotation is shown. A close agreement between the model and the measured reflectance spectra is obtained. In addition, the elytral surface of C. smaragdina possesses a blazed diffraction grating-like surface structure, which affects the diffuse appearance of the beetle's reflected colour, and therefore potentially enhances crypsis among the dense foliage of its rainforest habitat

Circularly polarised colour of the scarab beetle Chalcothea smaragdina: light scattering by a dual photonic structure

This is the author accepted manuscript. The final version is available from the Royal Society via the DOI in this record.Helicoidal architectures comprising various polysaccharides such as chitin and cellulose have been reported in biological systems. In some cases, these architectures exhibit stunning optical properties analogous to ordered cholesteric liquid crystal phases. In this work, we characterise the circularly polarised reflectance and optical scattering from the cuticle of the beetle Chalcothea smaragdina (Coleoptera: Scarabaeidae: Cetoniinae) using optical experiments, simulations and structural analysis. The selective reflection of left-handed circularly polarised light is attributed to a Bouligand-type helicoidal morphology within the beetle’s exocuticle. Using electron microscopy to inform electromagnetic simulations of this anisotropic stratified medium, the inextricable connection between the colour appearance of C. smaragdina and the periodicity of its helicoidal rotation is shown. A close agreement between the model and the measured reflectance spectra is obtained. In addition, the elytral surface of C. smaragdina possesses a blazed diffraction grating-like surface structure, which affects the diffuse appearance of the beetle’s reflected colour, and therefore potentially enhances crypsis amongst the dense foliage of its rainforest habitat.This work was financially supported by the National Centre of Competence in Research BioInspired Materials and the Ambizione program of the Swiss National Science Foundation SNSF (PZ00P2 168223, to BDW)

Glitter-like iridescence within the bacteroidetes especially Cellulophaga spp.: optical properties and correlation with gliding motility.

This is the final version of the article. Available from the publisher via the DOI in this record.Iridescence results from structures that generate color. Iridescence of bacterial colonies has recently been described and illustrated. The glitter-like iridescence class, created especially for a few strains of Cellulophaga lytica, exhibits an intense iridescence under direct illumination. Such color appearance effects were previously associated with other bacteria from the Bacteroidetes phylum, but without clear elucidation and illustration. To this end, we compared various bacterial strains to which the iridescent trait was attributed. All Cellulophaga species and additional Bacteroidetes strains from marine and terrestrial environments were investigated. A selection of bacteria, mostly marine in origin, were found to be iridescent. Although a common pattern of reflected wavelengths was recorded for the species investigated, optical spectroscopy and physical measurements revealed a range of different glitter-like iridescence intensity and color profiles. Importantly, gliding motility was found to be a common feature of all iridescent colonies. Dynamic analyses of "glitter" formation at the edges of C. lytica colonies showed that iridescence was correlated with layer superposition. Both gliding motility, and unknown cell-to-cell communication processes, may be required for the establishment, in time and space, of the necessary periodic structures responsible for the iridescent appearance of Bacteroidetes.PV acknowledges the support of AFOSR grant FA9550-10-1-0020. BK was a PhD student with a grant from the Ministe`re de la recherche et de l’enseignement supe´rieur. ER acknowledges the support of CNRS grant AIR75515 (‘‘Bacte´ridescence’’ project). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript

Structural colour from helicoidal cell-wall architecture in fruits of Margaritaria nobilis

The bright and intense blue-green coloration of the fruits of Margaritaria nobilis (Phyllanthaceae) was investigated using polarization-resolved spectroscopy and transmission electron microscopy. Optical measurements of freshly collected fruits revealed a strong circularly polarized reflection of the fruit that originates from a cellulose helicoidal cell wall structure in the pericarp cells. Hyperspectral microscopy was used to capture the iridescent effect at the single-cell level.This work was supported by the Leverhulme Trust (F/09- 741/G) and a BBSRC David Phillips fellowship (BB/K014617/1). P.V. acknowledges support from the US Air Force Office of Scientific Research under award number FA9550-10-1-0020. U.S. acknowledges support from the Adolphe Merkle foundation and the Swiss National Science Foundation through the National Centre of Competence in Research Bio-Inspired Materials

Nonlinear optical spectroscopy and two-photon excited fluorescence spectroscopy reveal the excited states of fluorophores embedded in a beetle's elytra

This is the author accepted manuscript. The final version is available via the DOI in this record.Upon illumination by ultraviolet light, many animal species emit light through fluorescence processes arising from fluorophores embedded within their biological tissues. Fluorescence studies in living organisms are however relatively scarce and so far limited to the linear regime. Multiphoton excitation fluorescence analyses as well as nonlinear optical techniques offer unique possibilities to investigate the effects of the local environment on the excited states of fluorophores. Herein, these techniques are applied for the first time to study of the naturally controlled fluorescence in insects. The case of the male Hoplia coerulea beetle is investigated because the scales covering the beetle's elytra are known to possess an internal photonic structure with embedded fluorophores, which controls both the beetle's coloration and the fluorescence emission. An intense two-photon excitation fluorescence signal is observed, the intensity of which changes upon contact with water. A third-harmonic generation signal is also detected, the intensity of which depends on the light polarization state. The analysis of these nonlinear optical and fluorescent responses unveils the multi-excited states character of the fluorophore molecules embedded in the beetle's elytra. The role of form anisotropy in the photonic structure, which causes additional tailoring of the beetle's optical responses, is demonstrated by circularly polarized light and nonlinear optical measurements.Wallonia–Brussels InternationalBelgian National Fund for Scientific Research2018 Biomimetics Travel AwardFWO FlandersHercules FoundationAction de Recherche ConcerteNanoscale Quantum OpticsFRSFNRSMinistry of Science, Republic of Serbi

Towards outperforming conventional sensor arrays with fabricated individual photonic vapour sensors inspired by Morpho butterflies.

Published onlineJournal ArticleResearch Support, Non-U.S. Gov'tResearch Support, U.S. Gov't, Non-P.H.S.Combining vapour sensors into arrays is an accepted compromise to mitigate poor selectivity of conventional sensors. Here we show individual nanofabricated sensors that not only selectively detect separate vapours in pristine conditions but also quantify these vapours in mixtures, and when blended with a variable moisture background. Our sensor design is inspired by the iridescent nanostructure and gradient surface chemistry of Morpho butterflies and involves physical and chemical design criteria. The physical design involves optical interference and diffraction on the fabricated periodic nanostructures and uses optical loss in the nanostructure to enhance the spectral diversity of reflectance. The chemical design uses spatially controlled nanostructure functionalization. Thus, while quantitation of analytes in the presence of variable backgrounds is challenging for most sensor arrays, we achieve this goal using individual multivariable sensors. These colorimetric sensors can be tuned for numerous vapour sensing scenarios in confined areas or as individual nodes for distributed monitoring.We would like to acknowledge H. Ghiradella (University at Albany), M. Blohm and S. Duclos (GE) and V. Greanya, J. Abo-Shaeer, C. Nehl and M. Sandrock (DARPA) for fruitful discussions. This work has been supported in part from DARPA contract W911NF-10-C-0069 ‘Bio Inspired Photonics’ and from General Electric’s Advanced Technology research funds. The content of the information does not necessarily reflect the position or the policy of the US Government