  This paper proposes a new method to achieve robust optical pulling of
particles by using an air waveguide sandwiched between two chiral hyperbolic
metamaterials. The pulling force is induced by mode conversion between a pair
of one-way-transport surface-arc waves supported on the two metamaterial
surfaces of the waveguide. The surface arcs bridge the momentum gaps between
isolated bulk equifrequency surfaces (EFSs) and are topologically protected by
the nontrivial Chern numbers of the EFSs. When an incident surface-arc wave
with a relatively small wavenumber $k_{x1}$ is scattered by the particle, a
part of its energy is transferred to the other surface-arc mode with
$k_{x2}(>k_{x1}). Because the electromagnetic wave acquires an additional
forward momentum from the particle proportional to $k_{x2}-k_{x1}$ during this
process, the particle will always be subjected to an optical pulling force
irrespective of its material, shape and size. Since the chiral surface-arc
waves are immune to backscattering from local disorders and the metamaterials
are isotropic in the xy plane, robust optical pulling can be achieved in a
curved air waveguide and can go beyond standard optical pulling mechanisms
which are limited to pull in a straight-line.
