POLARIZATION DEPENDENCE OF THE ELECTROMAGNETIC-FIELD DISTRIBUTION ACROSS WAVELENGTH-SIZED RELIEF GRATING SURFACES

The complex values of the surface electromagnetic fields of relief gratings for both TE and TM polarization are rigorously evaluated with use of the boundary-matching technique. The amplitude and phase of the surface field can be significantly modified by the edges and walls. The degree of modulation is strongly dependent on various factors, including the incident polarization. As the incident angle varies, the behavior of the surface-field amplitude is considered to be connected to the Brewster-angle effect. The complex refractive index of the grating material also influences the shape of the surface field but not in a proportional way. The oscillating surface fields with depth for both TE and TM polarization are explained as being due to secondary backward diffraction. In particular, as the edge and wall effects influence the TE and TM components differently, the oscillation peaks occur at different positions when TE and TM curves are compared.