The Faraday effect in three-dimensional opal photonic crystals

We have investigated the Faraday effect of three-dimensional photonic crystals, artificial opals immersed in a magnetoactive liquid. Faraday rotation was measured along high-symmetry points on the Brillouin zone surface of the opal lattice. It was shown that the behavior of the Faraday rotation spectrum taken along certain crystallographic direction strongly depends on photonic bandgaps of opal samples. The features observed in Faraday rotation spectra coincide with photonic bandgap minima.