title: Light trapping structures in wing scales of butterfly Trogonoptera brookiana.
abstract: The fine optical structures in wing scales of Trogonoptera brookiana, a tropical butterfly exhibiting efficient light trapping effect, were carefully examined and the reflectivity was measured using reflectance spectrometry. The optimized 3D configuration of the coupling structure was determined using SEM and TEM data, and the light trapping mechanism of butterfly scales was studied. It is found that the front and back sides of butterfly wings possess different light trapping structures, but both can significantly increase the optical path and thus result in almost total absorption of all incident light. An optical model was created to check the properties of this light trapping structure. The simulated reflectance spectra are in concordance with the experimental ones. The results reliably confirm that these structures induce efficient light trapping effect. This functional "biomimetic structure" would have a potential value in wide engineering and optical applications.
authors.affiliation: Key Laboratory of Bionic Engineering (Ministry of Education, China), Jilin University, Changchun 130022, PR China. zwhan@jlu.edu.cn
authors.forename: Zhiwu
authors.initials: Z
authors.lastname: Han
authors.forename: Shichao
authors.initials: S
authors.lastname: Niu
authors.forename: Chunhui
authors.initials: C
authors.lastname: Shang
authors.forename: Zhenning
authors.initials: Z
authors.lastname: Liu
authors.forename: Luquan
authors.initials: L
authors.lastname: Ren
mesh_terms: D000818:Animals; D040761:Biomimetic Materials / Q000737:chemistry; D002080:Butterflies / Q000737:chemistry*; D049329:Nanostructures / Q000737:chemistry / Q000648:ultrastructure; D014466:Ultraviolet Rays; D014921:Wings, Animal / Q000737:chemistry