Optical Zitterbewegung effect in arrays of helical waveguides

Owing to its topological properties and band collapse, Floquet helical photonic lattices have gained increasing attention as a purely classical setting to realize the optical analogues of a wide variety of quantum phenomena. We demonstrate both theoretically and numerically that light propagation in an appropriately designed helical superlattice can exhibit spatial photonic Zitterbewegung effect, i.e., a quiver spatial oscillatory motion of the beam center of mass around its mean trajectory, in both one- and two-dimensional cases. The lattice spacing determines the effective coupling strength between adjacent helical waveguides, and further drastically not only affects the oscillation amplitude and frequency, but also invert their direction of drift when the effective coupling strength is tuned from positive to negative. Complete arrest and inversion of the drift direction of Zitterbewegung effect are reported.