Modal theory for diffraction from a dielectric aperture with arbitrarily shaped corrugations

Abstract

The multilayer modal method is applied to solve the problem of scattering from a structure consisting of dielectric zones of constant refraction index in the aperture of a perfectly conducting screen. Adjacent zones are separated by arbitrarily shaped interfaces which are approximated by steps, forming a succession of rectangular layers. Making use of the R-matrix propagation algorithm, the fields are matched at each horizontal interface and the complete solution of the problem is found in terms of the reflected and transmitted amplitudes. Examples of the results are shown for finite dielectric gratings with different profiles and for both basic modes of polarization. In particular, curves of transmitted intensity versus transmission angle are discussed for structures with one and two grooves in a dielectric substrate.