Grating-coupled surface plasmons at microwave frequencies

This work presents a detailed investigation of electromagnetic coupling to the surface plasmon-polariton (SPP) at microwave frequencies. We have recorded the wavelength-dependent reflectivity from a metallic sinusoidal diffraction grating of pitch 15 mm. In order to minimize the problems associated with nonplanar incident wavefronts, we have developed an apparatus that collimates the incident beam. We illustrate resonant coupling to the SPP at wavelengths of the order of 10 mm. The wavelength-dependent reflectivities recorded have been successfully fitted using a differential formalism of conical diffraction with a single set of grating parameters describing the grating profile and metal permittivity. (C) 1999 American Institute of Physics. [S0021-8979(99)08215-8].