  We show the direct effect of free electrons colliding with polaritons,
changing their momentum. The result of this interaction of the electrons with
the polaritons is a change in the angle of emission of the photons from our
cavity structure. Because the experiment is a photon-in, photon-out system,
this is equivalent to optical beam steering of photons using a direct
electrical current. The effect is asymmetric, significantly slowing down the
polaritons when they move oppositely to the electrons, while the polariton
momentum only slightly increases when electrons moving in the same direction.
We present a theoretical model which describes this effect.
