Nonlinear transformation optics and engineering of the Kerr effect
  The concept of transformation optics is extended to nonlinear electrodynamics. It is shown that transformation optics favors implicit constitutive relations in terms of energy densities D.E and B.H rather than E^2 and H^2. The Kerr nonlinearity is studied in detail and the transformation optics based engineering of self-interaction effects is discussed. As a specific example we introduce transformation optics applied on a self-focusing field configuration. 
Luzi Bergamin, Pekka Alitalo, Sergei Tretyakov
physics.optics cond-mat.mtrl-sci