Nonlinear imaging in photonic lattices
  We show that nonlinear imaging is possible in periodic waveguide configurations provided that we use two different segments of nonlinear media with opposite signs of the Kerr nonlinearity with, in general, no other restriction about their magnitudes. The second medium is used to implement effective "reverse propagation". A main ingredient in achieving nonlinear imaging is the control of the sign and the amplitude of the coupling coefficient. We numerically test our results in one and two dimensional square arrangement of waveguides. 
Nikolaos K. Efremidis and Mihalis Mparkas
physics.optics nlin.PS