Proposed method for detection of the pseudospin-\({\scriptstyle \frac{1}{2}}\)Berry phase in a photonic crystal with a Dirac spectrum

The focusing of electric current by a single p-n junction in graphene is theoretically predicted. Precise focusing may be achieved by fine-tuning the densities of carriers on the n- and p-sides of the junction to equal values. This finding may be useful for the engineering of electronic lenses and focused beam splitters using gate-controlled n-p-n junctions in graphene-based transistors.