Disordered Field Patterns in a Waveguide with Periodic Surfaces

This paper considers an electromagnetic waveguide composed of two periodic, perfectly conducting, rippled surfaces. This periodic system has a band structure given by a dispersion relation that allows us characterize eigenmodes of the system. We considered the cases of both smooth and rough surfaces, using an integral numerical method to calculate field intensities corresponding to eigenmodes over a wide frequency range. Under certain conditions, the system presents disordered patterns of field intensities with smooth surfaces. We believe that the explanation of disordered patterns is the following: for smooth surfaces, the phenomenon of electromagnetic chaos; and for rough surfaces, the speckle phenomenon. Since it is well known that the surfaces of materials always have a certain degree of roughness, it can be concluded that both chaos and speckle contribute to the presence of disordered field patterns.