Fabrication and optimization of planar defects embedded between two silica opals

We present a versatile and efficient way to engineer a planar defect layer between two opal-based photonic crystals, leading to the appearance of a passband within the photonic stopband. The optimization of the planar defect parameters, necessary to preserve the high crystallographic order of the hetero-structures, is deduced from 1D-simulations of reflection spectra.