Light control in Ge_2Sb_2Te_5-coated opaline photonic crystals mediated by interplay of Wood anomalies and 3D Bragg diffraction

摘要

We present experimental and theoretical study of light reflection spectra from hybrid structures formed by Ge_2Sb_2Te_5 chalcogenide film on top of 3D opaline photonic crystal. We demonstrate the presence of diffraction anomalies (Wood anomalies) in the spectra. These anomalies are caused by the light scattering on the hybrid structure surface of hexagonal symmetry. To interpret the experimental results, we develop a qualitative theoretical model, taking into account the dispersion of quasi-waveguide modes supported by the surface layer of the hybrid structure. We consider the conditions for the coupling between the Bragg resonances associated with the diffraction of light on the 3D opal lattice and the resonances due to Wood anomalies.