Shock wave in Euler - Heisenberg - K\"ockel nonlinear vacuum
  An analytical approach to the theory of electromagnetic waves in nonlinear vacuum is developed. The evolution of the pulse is governed by a system of nonlinear wave vector equations. Exact solution with own angular momentum in form of a shock wave is obtained. 
Lubomir M. Kovachev, Daniela A. Georgieva, and Kamen L. Kovachev
physics.optics math-ph math.MP nlin.PS