Optical pulling using topologically protected one way transport surface-arc waves

Optical pulling is a counterintuitive phenomenon whereby light can pull particles against its propagation direction, but usually it is necessary to optimize both the incident beam and the manipulated particles. Here, we propose a robust optical pulling scheme using an air waveguide sandwiched between two chiral hyperbolic metamaterials carrying Weyl points. The pulling force is induced by mode conversion between two topologically protected chiral surface arcs supported on the two metamaterial surfaces of the waveguide. We prove that the optical pulling force is totally attributed to the Minkowski-type momentum of light and proportional to the wave-number difference between the two surface-arc waves, thus the pulling force is robust against the material, shape, and size of the particle. Thanks to the backscattering immunity of the surface-arc waves and the in-plane isotropy of the metamaterials, robust optical pulling can be achieved even in a curved waveguide, going beyond standard mechanisms of straight-line pulling.