  Optical pulling forces or tractor beams can pull particles against light
propagation by redirecting the incident photons forward. This is typically
achieved using Bessel beams with very small half-cone angles, which
considerably limits its applicability. One can circumvent such issue by using a
superposition of plane waves. In order to investigate optical pulling forces
exerted by a pair of non-colinear plane waves, we develop a theoretical
framework based on Mie theory, Debye potentials and Wigner rotation matrices.
We apply this framework to calculate the optical pulling force on
metallo-dielectric composite particles, which we put forward as an alternative
material platform to optimize and tailor tractor beams. Indeed we demonstrate
that by adding a few plasmonic inclusions to low-refractive index dielectric
particles of arbitrary sizes, we are able to produce polarization dependent
optical pulling forces that cannot occur in the corresponding homogeneous
particles. Altogether our findings not only provide innovative theoretical
methods to compute optical pulling forces, but also provide new strategies to
tailor and optimize them, paving the way to increase their applicability.
