Numerical analysis of the propagation of light in a disordered waveguide system

The propagation properties of light in a disordered waveguide system composed of randomly different cores in size are presented by numerically solving the coupled mode equation. The propagation constants of the modes are assumed to be a random variable. When one of cores is illuminated at the input end of the waveguide system the coherent part of the amplitude of light decreases exponentially with increasing distance and at large distance only the incoherent part propagates. The incoherent part is concentrated into a narrow region near the illuminated core in the cross section of the waveguide system and the distribution does not almost change along the waveguide axis.