  We investigate the process of coarsening via annihilation of
vortex-antivortex pairs, following the quench to the condensate phase in a
nonresonantly pumped polariton system. We find that the late-time dynamics is
an example of universal phase ordering kinetics, characterized by scaling of
correlation functions in time. Depending on the parameters of the system, the
evolution of the characteristic length scale L(t) can be the same as for the
two-dimensional XY model, described by a power law with the dynamical exponent
z \aprox 2 and a logarithmic correction, or z \aprox 1 which agrees with
previous studies of conservative superfluids.
