Nanoarchitecture in the black wings ofTroides magellanus: a natural case of absorption enhancement in photonic materials

Abstract

The birdwings butterfly Troides magellanus possesses interesting properties for light and thermal radiation management. The black wings of the male exhibit strong (98%) absorption of visible light as well as two strong absorption peaks in the infrared (3 µm and 6 µm) both due to chitin. These peaks are located in the spectral region where the black body emits at 313K. The study of absorption enhancement in this butterfly could be helpful to design highly absorbent biomimetic materials. Observations of the wings using a scanning electron microscope (SEM) reveal that the scales covering the wings are deeply nanostructured. A periodic three-dimensional (3D) model of the scale nanoarchitecture is elaborated and used for numerical transfer-matrix simulations of the absorption spectrum. The complex refractive index of the wing material is approximated by a multi-oscillator Lorentz model, leading to a broad absorption in the visible range as well as two peaks in the infrared. The absorption peak intensities turn out to be dependent on the complexity of the nanostructures. This result clearly demonstrates a structural effect on the absorption. Finally, a comparison with a planar layer of identical refractive index and material volume lead us to conclude that the absorption is enhanced by nanostructures.

Infrared-induced variation of the magnetic properties of a magnetoplasmonic film with a 3D sub-micron periodic triangular roof-type antireflection structure

“…The fluctuation of the absorption spectra at 860 nm is due to the transformation of the light source in the spectrophotometer. In the absorption spectra, we can observe that the T_FW exhibits superior light absorption capability in the visible light region because of the coupling effect between the melanin/chitin composite and the SPTAS 20 21 . Compared with the absorption properties of the T_FW, the carbonized T_FW (C_T_FW) shows an enhancement in absorption in the IR region, demonstrating that amorphous carbon provides better IR absorption than the melanin/chitin composite of the T_FW.…”

“…The ridges, microribs and windows construct a SPTAS that effectively traps light. The combination of a melanin/chitin composite with this SPTAS endows the black T_FW with an effective visible light trapping capability 20 21 . The SEM image of chitin-matrix Ni wing_6h clearly shows that the Ni NPs deposited onto the surface and assembled into a film that successfully inherited the SPTAS of the T_FW scale ( Figure 2(b) ).…”

“…To combine magnetic and plasmonic functionalities, we fabricated a carbon-matrix nickel composite magnetoplasmonic film (CNMF) with a 3D sub-micron periodic triangular roof-type antireflection structure (SPTAS) using a simple and promising method that combines chemosynthesis with biomimetic techniques and uses the Troides helena forewing (T_FW) as a biomimetic template. Because the black T_FW possesses an effective visible light trapping capability due to the melanin/chitin composite contained in this SPTAS 20 21 22 . The CNMF exhibits enhanced infrared (IR) absorption over a broad wavelength range.…”

Hydrothermal Synthesis Au-Bi2Te3 Nanocomposite Thermoelectric Film with a Hierarchical Sub-Micron Antireflection Quasi-Periodic Structure

“…The ridges, microribs and windows construct a hierarchical sub-micron antireflection quasi-periodic structure (HSAQS) that effectively traps light. The combination of a melanin/chitin composite with this HSAQS endows the black T_FW with an effective visible light trapping capability [ 28 , 40 , 42 ]. From the SEM images of Au-Bi 2 Te 3 _T_FW ( Figure 1 d–f), these figures clearly exhibit that the Au-Bi 2 Te 3 nanocomposite were deposited and agglomerated into thin film on the ridges and microribs.…”

“…Based on the antireflection and photoabsorption structure, the black butterfly wings exhibited extreme absorption in the visible range of the solar spectrum and an effective photothermal conversion performance, which uses the absorbed energy to warm up the muscle before flying [ 42 , 43 ]. Here, we combine the Au-Bi 2 Te 3 nanocomposite thermoelectric film (ABTEF) with the antireflection and photoabsorption structure of black butterfly wings to prepare an Au-Bi 2 Te 3 nanocomposite photo-thermal voltaic film (Au-Bi 2 Te 3 _T_FW).…”