Fig. 2: Energy spectrum and beam propagation for topological pumping.
From: Asymmetric topological pumping in nonparaxial photonics
The energy spectrum for a conventional Rice-Mele model without next-nearest-neighbor (NNN) hopping, and b, c extended Rice-Mele model with positive (κNNN = 0.007 mm−1) and negative (\({\tilde{\kappa }}_{{{{\rm NNN}}}}={{{{{{{\rm{-}}}}}}}}0.007  {{{\rm{mm}}}}^{-1}\)) NNN hopping terms, respectively. Two symmetric pump channels are shown in a but only one of the channels (b, c) remains when adding the NNN hopping. Correspondingly, the beam propagation on these photonic lattices demonstrate two symmetric pumping in d and asymmetric pumping in e, f. The beam propagation in the blocked channels [the upper panel in e, and the lower panel in f] show the topological edge state confinement along the array boundaries. The simulation parameters are taken from the experiment.
