Anisotropy of weak light scattering in thin opal films

Abstract

The forward and backward light scattering that accompanied the almost ballistic light propagation in opal-based three-dimensional photonic crystal (PhC) has been experimentally studied. The light path memory and the high anisotropy of scattering have been associated with low-order scattering at large-scale crystal defects. The strong backscattered light intensity has been linked to the uncoupled light at a PhC surface. The exponent of power-law approximation of angle diagrams of the scattered light intensity has been suggested as a measure of the scattering anisotropy. The scattering anisotropy spectra have demonstrated that in a vicinity to the first photonic bandgap, the lower directionality of the forward scattering is complemented by the higher directionality of the backward scattering

Interplay of index contrast with periodicity in polymer photonic crystals

“…3(d)), with the exception of the lowest index-contrast sample. These observations contrast with those on high Dn opals, which exhibit an additional isotropic surface scattering that leads to spectral dips, 15 rather than the scattering peaks we always observe. Further theoretical and experimental investigation is required to fully explain the origin of this cone width, which is related to the lateral scale length of disorder in the samples.…”

“…This is because both the Bragg length, of order L B ¼ kDn/n av , and the mean free path are smaller than the ordered opal thickness for all of the Dn values under study. 14,15 Hence, the degree of disorder in the sample demonstrably plays a fundamental role in these linear dependencies. In previous studies of polymer opals, we presented crystallographic evidence of stacking faults and/or twinning within the cubic structures, which introduces a certain level of disorder throughout the films.…”

Broadband Omnidirectional Diversion of Light in Hybrid Plasmonic‐Photonic Heterocrystals

“…This conversion also applies to the diffraction orders, the lateral propagation of which approaches the angle of total internal reflection at the opal‐air interface. Thus, two loss mechanisms cooperate in the bare opal film: i) coherent scattering to diffraction orders of high‐index planes and ii) diffuse scattering of the incident beam and its diffraction orders42 ( Figure ). The polarization dependence of light transport in opals is reasonably weak at frequencies away from diffraction resonances 43.…”