Flexible electromagnetic manipulation by topological one-way large-area waveguide states

In this work, we propose a way to achieve flexible long-range and large-area electromagnetic (EM) manipulation by using a pair of topological one-way large-area waveguide states (TOLWSs) propagating in the same direction in a photonic crystal ABC heterostructure. Due to the topological protection of TOLWSs, backscattering is forbidden against the local perturbation during their propagation. When one of them is excited, the particle located in the middle B area results in scattering between two copropagating TOLWSs. This mode-conversion effect leads to flexible EM manipulation, i.e., the particle can be pulled or pushed towards or away from the source depending on its frequency and mode. Furthermore, it is also found that the directions of the longitudinal EM force also depend on the constituent materials of the particles, which suggests a particle-sorting mechanism based on TOLWSs. More importantly, as a demonstration of multiparticles' EM simultaneous manipulation via TOLWSs, the EM forces of two and three particles located in the B region are calculated and studied. It is found that both particles can be pulled or pushed at the same time. Our work paves the way for the potentially important application of TOLWSs in EM manipulation, which is expected to be realized in the experiment in the near future.