Anti-reflective properties of butterfly-wing-micro-nano structures in the infrared band

•The structural-color scales of butterfly Papilio epiphorbas, butterfly Parthenos syvia, and butterfly Sasakia charonda can achieve a better anti-reflection effect in the infrared band. Among them, the anti-reflective performance of the three butterfly scales was ranked as follows: blue-green scales of butterfly Papilio epiphorbas vermilion > purple scales of butterfly Parthenos syvia > green scales of butterfly Sasakia charonda; The average reflectance in the measured wavelength range is 6.24%, 7.39%, and 14.21% respectively.•The surface's micro-nano structure mainly determines the butterfly surface's anti-reflective properties. By extracting and simplifying the micro and nanostructures, three kinds of anti-reflection structures were obtained: conical hole structure, grating tower structure, and rectangular groove structure.•Numerical analysis methods using finite differences in the time domain, the reflectance characteristics of the micro - nano-structure surface of the butterfly wings of butterfly Papilio epiphorbas, butterfly Parthenos syvia, and butterfly Sasakia charonda were simulated and calculated. By simulating the structure parameters of the conical hole structure, the grating tower structure, and the rectangular groove structure: the structure diameter, bottom edge, side length, structure depth, and so on, the results show that the simplified structure is more conducive to anti-reflection. The reflectance of the butterfly wing is reduced by 0.34%, 2.44%, and 5.46%, respectively.•Structures with gradient changes (conical hole structure of butterfly Papilio epiphorbas and grating tower structure of butterfly Parthenos syvia) have better anti-reflection performance than non-gradient structures (rectangular groove structure of butterfly Sasakia charonda). And it is concluded that when analyzing the relationship between structural spacing and reflectivity for structures with gradients, equating them to gradient-free structures for calculating the equivalent refractive index is an effective method of determining the antireflective properties.