  Focusing of electron waves in graphene p-n junctions is a striking
manifestation of fermionic negative refraction. We analyze lensing in smooth
p-n junctions and find that it differs in several interesting ways from that in
the previously studied sharp p-n junctions. Most importantly, while the overall
negative-refraction behavior remains unchanged, the image at the focal point
undergoes additional broadening due to Klein tunneling in the junction. We
develop a theory of image broadening and estimate the effect for practically
interesting system parameter values.
