Figure 2: Numerical simulation of pseudospin-mediated vortex generation in photonic graphene.

(a) The honeycomb lattice, and (e) the input triangular lattice as a probe formed by three-beam interference. (b,f) Superimposed patterns (zoomed in) when only sublattice A (top row) or B (bottom row) is excited. The output intensity patterns of the probe beam exhibit similar conical diffraction (c,g), but the interferograms obtained with an inclined plane wave reveal opposite phase singularities in the centre (d,h) due to excitation of different pseudospin states (Parameters for simulation are chosen close to those from experiment: the lattice spacing is 7 μm, the strength of refractive index modulation is 2 × 10⁻⁴ and the propagation distance is 20 mm).