Relativistic regimes for dispersive shock-waves in non-paraxial   nonlinear optics
  We investigate the effect of non-paraxiality in the dynamics of dispersive shock waves in the defocusing nonlinear Schroedinger equation. We show that the problem can be described in terms of a relativistic particle moving in a potential. Lowest order corrections enhance the wave-breaking and impose a limit to the highest achievable spectrum in an amount experimentally testable. 
Silvia Gentilini, Eugenio DelRe and Claudio Conti
physics.optics