Optical costs and benefits of disorder in biological photonic crystals

Abstract

Photonic structures in ordered, quasi-ordered or disordered forms have evolved across many different animals and plant systems. They can produce complex and often functional optical responses through coherent and incoherent...

Mechanisms involved in the production of differently colored feathers in the structurally colored swallow tanager (Tersina viridis; Aves: Thraupidae)

“…However, the regulatory processes leading to changes in structural coloration are still vastly unknown. The spongy matrix needs to be quasi‐ordered to produce structural colors in the plumage (Mouchet et al, 2020; Prum, 2006). The wavelengths reflected by this structure depend mostly on the size and spacing between air spaces in the spongy matrix (Parnell et al, 2015; Saranathan et al, 2012; Stavenga et al, 2011).…”

Reindeer eyes seasonally adapt to ozone-blue Arctic twilight by tuning a photonic tapetum lucidum

“…The latter is due to tighter positional constraints imposed by the approach to the closest possible packing where the fibrils are essentially in contact in a hexagonal pattern. The increase in regularity of fibril spacing narrows the bandwidth in wavelength but retains a saddle that bridges the first and second orders [ 21 ]. While the first-order peak in winter matches the spectral distribution of twilight, the extension of the saddle towards the second-order peak in the UV maintains the efficacy of the tapetum down to a wavelength of around 350 nm where collagen begins to absorb but where the reindeer retina retains good sensitivity [ 16 ].…”

3D tomographic analysis of the order-disorder interplay in the Pachyrhynchus congestus mirabilis weevil

“…Some part of the distribution width of the measured quantities can be attributed to the data acquisition and reconstruction processes, combined with topological and positional defects accounting for grain boundaries and other inherent imperfections, and defects from the biological processes that generated the network structures (28,41,42).Since these contributions should be identical for both systems, the wider spread observed for all measured quantities in the blue scale can be ascribed to a higher 'disorder'. The difference is most notable in the dihedral angle distribution, which is coherent with decreasing structural correlations on medium to long length scales.…”

“…Nevertheless, at low wavelengths, the PDOS values are significantly lowered with respect to the homogeneous medium, giving rise to a broad partial bandgap ranging from 400 to 595 nm, in accordance with the simulated reflection peak of the corresponding structure. Although a bandgap is expected for a 'perfect' diamond, the partial bandgap of the ordered structure shows a high resilience of the optical properties with respect to structural imperfections, such as grain boundaries, imperfect periodicity, positional and topological defects (41). In an amorphous medium, the incoming light undergoes strong isotropic scattering usually resulting in white coloration.…”