Artificial opal films have been prepared by sedimentation of monodisperse silica spheres in water suspension. Atomic force microscope images show a triangular packing of the spheres at the surface of the films. The presence and the energy position of an optical pseudo gap in incidence-angle-dependent transmittance and reflectance spectra is observed and accounted for by theoretical calculations of the photonic band structure. These calculations indicate that the pseudo gap is due to the splitting of the photonic bands in the L point of the Brillouin zone. The spectroscopic data show additional loss structures due to both other features of the Brillouin zone and the diffraction of the light from the regular surface of the sample. The effect of the infiltration of opals with polydiacetylene solutions is also reported.
OPTICAL STUDIES OF ARTIFICIAL OPALS AS 3D PHOTONIC CRYSTALS
COMORETTO, DAVIDE;DELLEPIANE, GIOVANNA;
2002-01-01
Abstract
Artificial opal films have been prepared by sedimentation of monodisperse silica spheres in water suspension. Atomic force microscope images show a triangular packing of the spheres at the surface of the films. The presence and the energy position of an optical pseudo gap in incidence-angle-dependent transmittance and reflectance spectra is observed and accounted for by theoretical calculations of the photonic band structure. These calculations indicate that the pseudo gap is due to the splitting of the photonic bands in the L point of the Brillouin zone. The spectroscopic data show additional loss structures due to both other features of the Brillouin zone and the diffraction of the light from the regular surface of the sample. The effect of the infiltration of opals with polydiacetylene solutions is also reported.
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