Spectra of the light scattered in the heterogeneous photonic crystal based on the thin triple-film opal, which was prepared by successive, convective force-assisted crystallisation of colloidal suspensions containing spheres of 374, 474 and again 374 nm in diameter, have been studied in the wavelength range of low order photonic bandgaps. If the ballistic regime of light propagation is preserved, the forward scattered light becomes the subject of the diffraction attenuation, whereas the backscattered light experiences both the diffraction enhancement and attenuation. A variety of possible configurations of scattered light measurements have been examined and corresponding spectra of scattered light have been compared with each other and with the spectra of transmitted and reflected light. The effect of the internal interfaces and the planar microcavity embedded in the photonic crystal upon the propagation of scattered light has been extracted.
We report on fabrication of high quality opaline photonic crystals from large silica spheres, self-assembled in hydrophilic trenches of silicon wafers by using a drawing apparatus with a combination of stirring. The achievements here reported comprise a spatial selectivity of opal crystallization without special treatment of the wafer surface, a filling of the trenches up to the top, leading to a spatially uniform film thickness, particularly an absence of cracks within the size of the trenches, and finally a good three-dimensional order of the opal lattice even in trenches with a complex confined geometry, verified using optical measurements. The opal lattice was found to match the pattern precisely in width as well as depth, providing an important step towards applications of opals in integrated optics. The influence of substrate structure on crystallization is also discussed.