  We study Veselago lensing of massless Dirac fermions by n-p junctions for
electron sources with a certain polarization. This polarization corresponds to
pseudospin for graphene and to real spin for topological insulators. Both for a
point source and for injection into a sample through a narrow lead, we find
that polarization leads to spatial symmetry breaking. For the Green's function,
this results in a vertical displacement, or even complete vanishing of the main
focus, depending on the exact polarization. For injection through a lead, it
leads to a difference between the amounts of current emitted with positive and
negative transversal momenta. We study both systems in detail using the
semiclassical approximation. By comparing the results to the exact solutions,
we establish that semiclassical methods provide a very effective way to study
these systems. For the Green's function, we derive an easy-to-use analytical
formula for the vertical displacement of the main focus. For current injection
through a lead, we use semiclassical methods to identify two different
scattering regimes.
