We have studied enhanced backscattering of both polystyrene opals and strongly photonic
crystals of air spheres in TiO2 in the wavelength range of first and higher order stop bands.
The shape of the enhanced backscattering cones is well described by diffusion theory. We
find transport mean free paths of the order of 15 μm both for opals and air spheres. Close to
the stop band the cone width is decreased due to internal reflections generated by the
photonic band structure. Widening occurs due to attenuation of the coherent beam by Bragg …