Optical response of a disordered bicontinuous macroporous structure in the longhorn beetle Sphingnotus mirabilis

We studied the structural and optical properties of scales in the longhorn beetle Sphingnotus mirabilis. Structural characterizations revealed that the scale interior possesses a disordered bicontinuous macroporous structure, resembling a phase-separated structure obtained by spinodal decomposition. Its optical response was investigated both experimentally and theoretically. Our results show that this structure has interesting optical properties due to the existence of only short-range order and the lack of well-defined local structures.