Energy redistribution and polarization transformation in conical mount diffraction under resonance excitation of surface waves

This paper presents an analytical theory of resonance diffraction in the conical mount. The resonance is caused by plasmon polariton excitation via diffraction from a highly reflecting shallow grating of arbitrary profile. Single and double resonance configurations are considered in detail. The dependence of polarization, intensity, and phase of specular and resonance waves on the parameters of the problem is presented in explicit form and examined for arbitrary polarization of the incident wave as a function of the angle of incidence and the grating period, orientation, form, and height. The results obtained enable us to indicate gratings with specific properties, for instance, gratings, ensuring transformation of arbitrarily polarized incident wave into the linearly polarized specular wave. Properties of two-dimensional transformation matrix relating polarization amplitudes of incident and specular reflected waves are analyzed. It is shown that the transformation matrix is antisymmetric even for asymmetric gratings (for symmetric gratings, this property is exact one, and it follows from the reciprocity theorem) for an arbitrary grating profile. The comparison of the results obtained shows the remarkable agreement with the data of the polarization conversion experiments. Both concrete results and the approach presented may be of use in constructing gratings with unique parameters and, therefore, in solving problems of designing optical devices, which are selective with respect to the polarization, wavelength, and orientation.