  We calculate the dispersion of spinor exciton-polaritons in a planar
microcavity with its active region containing a single Transitional Metal
Dichalcogenide (TMD) monolayer, taking into account excitonic and photonic
spin-orbit coupling. We consider the radial propagation of polaritons in
presence of disorder. We show that the reduction of the disorder scattering
induced by the formation of polariton states allows to observe an optical
Valley Hall effect, namely the coherent precession of the locked valley and
polarization pseudospins leading to the formation of spatial valley-polarized
domains.
