Transmission Anisotropy in Triple-Film Opal Photonic Crystals

Summary form only given: For photonic crystals (PhCs) to have successful impact on advancement of optical circuits and realisation of various functionalities, the incorporation of artificial defects into 3D PhCs is necessary. Opal films represent a convenient approach to the realisation of 3D PhCs. Taking into account the limited flexibility of the self-assembly, the first steps can be studies of planar defects in opals and hetero-opals. Characterisation of heteroPhCs should include the investigation of the dispersion of photonic bandgaps (PBG). While the dispersion of low-order PBGs in opal films is well known, the high order PBGs were hardly studied so far owing to high requirements to the crystallinity of PhCs. Correspondingly, the whole issue remains to be studied in hetero-opals. The obvious consequence of assembling of opal films with different lattice constants upon the spectra of transmitted light is the accumulation of all PBG features originating from each film in a heterostructure in the detected signal. In particular, the questions of genuine interest for designing novel photonic materials are whether the total transmission of the heterostructure will be a linear superposition of partial transmission spectra of opal films or it will demonstrate some novel features originating from the collective superstructure effects, whether the mode mismatch at interfaces or microcavity resonances will dominate the light transport and so on. We report angle-resolved optical transmission of triple-film hetero-opal in a broad spectral range including several photonic band gaps along LKL´ and LUX directions on the Brillouin zone surface. The polarisation-dependent dispersion of transmission minima and angular diagrams of transmission in the triple-film opal have been compared to that of constituent single-film opals. The validity of superposition approach to the description of the hetero-opal properties has been examined. Alteration of the transmission in hetero-opal, - uch as the decrease of the polarization anisotropy and narrowing of the transmission minima, has been explained by the presence of interfaces. The transmission attenuation has been linked to the transmission minimum width and dispersion