COMPARISON OF METAL PARAMETERS OBTAINED FROM PRISM AND GRATING COUPLING TO SURFACE-PLASMON POLARITONS

Surface plasmon polariton resonances obtained from both prism coupling (in the Otto configuration) and grating coupling to the same metallic surface have been fitted using appropriate theories to give the dielectric constant of the metal at 632.8 nm. Results from silver, aluminium and gold samples have confirmed that the dielectric constants obtained from fitting the data obtained using grating coupling are the same (to within experimental errors) as those obtained from prism-coupled data. This confirms for the first time the validity of the differential diffraction grating theory by direct comparison with known data for a metallic surface.