Diffraction imaging of cracks in self-assembled photonic crystals

Abstract We demonstrate a non-invasive technique, based on diffraction imaging, to remotely detect and characterize cracks in self-assembled photonic crystals. Through this technique, we measure the diffraction pattern of the cracks and determine how the orientation of the cracks varies across the sample. In particular, we characterize cracks in photonic crystals fabricated using evaporation-induced self-assembly process on a horizontal substrate. The morphological details of cracks obtained using our imaging technique match well with scanning electron microscopy images. We also develop a model for the surface of these crystals and calculate Fraunhofer diffraction patterns, using two-dimensional Fourier transform, that match well with our experimental observations.