Collimation and imaging behind a woodpile photonic crystal

We investigate different linear effects that appear in the light beam propagation behind a three-dimensional woodpile photonic crystal. On one hand we report and analyse experimental observation of narrow and well collimated laser beam formation behind the photonic crystal. We show that this collimation depends on the input laser beam focusing conditions. On the other hand we also report the first theoretical and numerical observation double imaging formation behind the photonic crystal. That conclusion comes from the idea that the spatial dispersion possess multiple branches (Bloch branches), generally of different curvatures, for a fixed frequency.