Imaging properties of photonic crystals

We observe, by means of finite element calculations, that some photonic crystals produce negative refraction with almost circular isofrequency lines of their band diagram, so that a slab of this structure presents a large degree of isoplanatism and thus can behave like an imaging system. However, it has aberrations on comparison with a model of ideal lossless left-handed material within an effective medium theory. Further, we see that it does not produce subwavelength focusing. We discuss the limitations and requirements for such photonic crystal slabs to yield superresolved images of extended objects.