The Goos-Hänchen (GH) effect is an interference effect on total internal reflection at an interface, resulting in a shift sigma of the reflected beam along the interface. We show that the GH effect at a p-n interface in graphene depends on the pseudospin (sublattice) degree of freedom of the massless Dirac fermions, and find a sign change of sigma at angle of incidence alpha=arcsin sqrt[sinalpha{c}] determined by the critical angle alpha{c} for total reflection. In an n-doped channel with p-doped boundaries the GH effect doubles the degeneracy of the lowest propagating mode, introducing a twofold degeneracy on top of the usual spin and valley degeneracies. This can be observed as a stepwise increase by 8e;{2}/h of the conductance with increasing channel width.

We calculate the effect of a Dirac point ͑a conical singularity in the band structure͒ on the transmission of monochromatic radiation through a photonic crystal. The transmission as a function of frequency has an extremum near the Dirac point, depending on the transparencies of the interfaces with free space. The extremal transmission T 0 = ⌫ 0 W / L is inversely proportional to the longitudinal dimension L of the crystal ͑for L larger than the lattice constant and smaller than the transverse dimension W͒. The interface transparencies affect the proportionality constant ⌫ 0 , and they determine whether the extremum is a minimum or a maximum, but they do not affect the "pseudodiffusive" 1 / L dependence of T 0 .

We propose a method to detect the geometric phase produced by the Dirac-type band structure of a triangular-lattice photonic crystal. The spectrum is known to have a conical singularity (= Dirac point) with a pair of nearly degenerate modes near that singularity described by a spin-1 2 degree of freedom (= pseudospin). The geometric Berry phase acquired upon rotation of the pseudospin is in general obscured by a large and unspecified dynamical phase. We use the analogy with graphene to show how complementary media can eliminate the dynamical phase. A transmission minimum results as a direct consequence of the geometric phase shift of π acquired by rotation of the pseudospin over 360 • around a perpendicular axis. We support our analytical theory based on the Dirac equation by a numerical solution of the full Maxwell equations.

Spin precession has been used to measure the transmission time τ over a distance L in a graphene sheet. Since conduction electrons in graphene have an energy-independent velocity v, one would expect τ ≥ L/v. Here we calculate that τ < L/v at the Dirac point (= charge neutrality point) in a clean graphene sheet, and we interpret this result as a manifestation of the Hartman effect (apparent superluminality) known from optics.

Photonic crystals with a two-dimensional triangular lattice have a conical singularity in the spectrum. Close to this so-called Dirac point, Maxwell's equations reduce to the Dirac equation for an ultrarelativistic spin-1/2 particle. Here we show that the half-integer spin and the associated Berry phase remain observable in the presence of disorder in the crystal. While constructive interference of a scalar (spin-zero) wave produces a coherent backscattering peak, consisting of a doubling of the disorder-averaged reflected photon flux, the destructive interference caused by the Berry phase suppresses the reflected intensity at an angle which is related to the angle of incidence by time-reversal symmetry. We demonstrate this extinction of coherent backscattering by a numerical solution of Maxwell's equations and compare with analytical predictions from the Dirac equation.