Light propagation in square law media with random imperfections

This paper investigates the deformation of the eld transmitted through a square law medium waveguide. We consider the situation where the center of the waveguide randomly oscillates around the optical axis or the radius of the waveguide randomly pulsates. The random perturbations are small, but the waveguide is long, which gives rise to a macroscopic eeect of the inhomogeneities. This eeect is characterized by coupling mechanisms between optical modes, which tend to strengthen high order modes. Precise expressions for the transmitted wave are derived which exhibit remarkable regimes, where behaviors such as shift, spreading or even focusing of the eld can be observed. Numerical simulations are in good agreement with the theoretical results.