Diffraction Grating Characterization Using Multiple-wavelength Excitation of Surface Plasmon Polaritons

Abstract

In this work we have used the optical excitation of surface plasmon polaritons to characterize the profile of a diffraction grating with a large groove-depth-to-pitch ratio at wavelengths spanning the visible spectrum. This provides us with confirmation of the accuracy of the modelling theory used to predict the optical response of a deep grating. In addition it draws attention to a particular wavelength regime which proves sensitive to the higher harmonics of the grating profile.