Spectral selectivity of 3D magnetophotonic crystal film fabricated from single butterfly wing scales

Abstract

3D magnetophotonic crystal (3D-MPC) film is an excellent platform for tailoring the magneto-optical response of magnetic materials. However, its fabrication is a great challenge due to the limitation of commonly used artificial synthesis methods. Inspired by the unique structures of biospecies, we hereby manipulate the pristine single wing scales of Morpho didius precisely and successfully fabricate Fe₃O₄ films with photonic structure. The synthesis strategy involves the fabrication of Fe₂O₃ film from a single wing scale using an improved sol–gel method followed by a subsequent reduction. The intrinsic hierarchical photonic structures as well as the anisotropic optical properties of the pristine butterfly wing scale have been retained in the obtained Fe₂O₃ and Fe₃O₄ films. When investigated under an external magnetic field, a spectral blue shift about 43 nm is observed in the designated orientation of the Fe₃O₄ film, which is useful for the design and creation of novel magnetic-optical modulator devices. Furthermore, these single scales can be used as building blocks to fabricate designable and more complicated assembled nano systems. This biomimetic technique combined with the variety of structures of butterfly wing scales provides an effective approach to produce magneto-photonic films with desired structure, paving a new way for theoretical research and practical applications.