The analysis of some exact solutions of Einstein equations, describing gravitational waves produced by light, shows that there can be repulsion between light beams. This is due only to the spin-1 character of the solutions and not to the introduction of other inputs external to General Relativity. Cosmological relativistic jets give an example of a such phenomenon.
Giovanni Sparano. Gaetano Vilasi. "Repulsive Gravity of Light Beams." J. Geom. Symmetry Phys. 32 37 - 50, 2013. https://doi.org/10.7546/jgsp-32-2013-37-50