  Recent advances in nanophotonics have brought about coherent light sources
with chaotic circular polarization; a low-dimensional chaotic evolution of
optical spin was evidenced in laser diodes. Here we propose a mechanism that
gives rise to light with a spatiotemporal spin chaos resembling turbulent
states in hydrodynamics. The spin-chaotic radiation is emitted by exciton
polaritons under resonant optical pumping in arbitrarily sized planar
microcavities, including, as a limiting case, pointlike systems with only three
degrees of freedom. The underlying mechanism originates in the interplay
between spin symmetry breakdown and scattering into pairs of Bogolyubov
excitations. As a practical matter, it opens up the way for spin modulation of
light on the scale of picoseconds and micrometers.
