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Free keywords:
opals; photonic crystals; polarization-resolved spectroscopy; anisotropy; band structure
Abstract:
Photonic crystals is expected to be the backbone of future optical integrated circuits. To realize this goal, light propagation and interaction with matters must be understood and controlled. In this work, we investigate the propagation of light inside opal-based photonic crystals along certain paths at the edge of its Brillouin Zone. Opal films made of polystyrene particles were prepared using self-assembly approach, the capillary deposition method. The structures and the optical properties of the resulting opals were characterized using scanning electron microscopy and polarization-resolved spectroscopy, respectively. The opal films have a face-centered cubic structure consisting of two domains showing preferential orientations. Domains in the form of ABC and ACB-type fcc crystals are oriented along the growth direction of the opal films. Light with frequencies near optical band gap shows a strong anisotropy. Light propagation inside opals depends on the polarization of the incident light. The intensity and the width of the extinction peaks for p-polarized incident light differ significantly from those of s-polarized light. The anisotropy disappears at frequencies above the optical band gap. The anisotropic light propagation is related to the strong anisotropy in equifrequency surface of band structure around the band gap. The shift of the extinction peaks and the variation of intensity of the extinction peaks will be discussed using the combination of kinematic and simplified dynamical diffraction theory.
