Quasi-incoherent propagation in waveguide arrays

In this letter a quasi-incoherent propagation in waveguide arrays is theoretically derived and experimentally verified. Depending on the initial light distribution the propagation in a waveguide array after multiwaveguide excitation exhibits an interference pattern or not. For the experimental verification the waveguide array is realized in OH rich fused silica by femtosecond laser direct writing. The light propagation within the array is directly visible due to the fluorescence of the created color centers. A precise excitation of different waveguides is achieved using a phase grating. (c) 2007 American Institute of Physics.