Enhanced backscattering from one-dimensional free-standing dielectric film

It has been known for several years that not only a rough metallic surface but also a rough dielectric surface can produce an enhanced backscattering peak. Due to the difficulty in fabricating one- or two-dimensional dielectric rough surfaces with a high index of refraction or a free-standing film, no experiments have been able to reveal such a peak in scattering from a dielectric rough surface. In this paper the authors present experimental results of the enhanced backscattering from a free-standing dielectric film and compare these with theoretical analysis. The vacuum/dielectric interface is one-dimensional, randomly rough, while the second dielectric/vacuum interface is approximately planer. The numerical simulations for a one-dimensional, randomly rough free-standing dielectric film reveal some important information about the main mechanism for the enhanced backscattering peak, primarily the presence of the flat dielectric/vacuum interface. The authors believe that the coherent addition from a given light path that interacts with the rough dielectric surface at two different points due to its reflection from the back surface and its time-reversed partner leads to an enhancement of the intensity of scattering into the retroreflection direction with respect to the intensity of scattering into other directions