Abstract
By a rigorous numerical simulation based on the standard multiple scattering theory, we investigate optical transmission in photonic crystal structures, formed from dielectric cylinders embedded in parallel in a uniform medium. In contrast to previous conjectures, the results indicate that the imaging effect of a flat photonic crystal slab, which has been interpreted as a signature of negative refractive effects, is caused by a tunneling or self-guiding effect in the presence of partial band gaps.