Figure 3: Experimental observation of vortex generation by initial excitation of three Dirac points.
From: Unveiling pseudospin and angular momentum in photonic graphene
(a) The honeycomb lattice optically induced in a nonlinear crystal, and (e) the probe beam at the input to the lattice containing no phase singularity. (b) Measured Brillouin zone spectrum of the induced lattice, and (f) the k-space spectrum of the input beam matching the three marked Dirac points in b. The white dashed lines mark the first BZ. (c,g) Output intensity patterns when only sublattice A (top row) or B (bottom row) is excited. The inserts illustrate the selective excitation of two sublattices by the probe beam corresponding to Fig. 2, which leads to opposite vortex singularities as identified from the interferograms (d,h).
