Linear and Nonlinear Optical Properties of Surface - Polaritons at Nanostructured Surfaces: Theory and Experiment.

Novel optical phenomena arising from diffractive coupling of an electromagnetic wave to the surface-plasmon polariton (SPP) at a weakly-corrugated metal surface are revealed through theoretical and experimental investigations. Original contributions have been made in three principal areas: (1) SPP-enhancement of second harmonic diffraction (SHD, (2) minigap phenomena, and (3) SPP-modulated metal deposition. Rigorous diffraction theories, which describe photon-SPP coupling at nanostructured surfaces, have permitted the prediction and elucidation of near- and far-field phenomena. Surface structures of interest have been fabricated by Fourier blaze holography (FBH), which permits spatial harmonic synthesis of arbitrary periodic structures. The investigation of SPP-enhanced SHD has revealed the utility of a novel optical effect--termed selective enhancement, a polological interpretation of the optimum corrugation amplitude for SHD, and the influence of SPP double resonance. Selective enhancement, which arises from selective scattering by spatial harmonics of either an SPP or a coherently-generated, SPP-enhanced, second harmonic evanescent wave, allows maximization of SPP-enhancement of SHD and provides a sensitive probe of spatial harmonic composition for weakly-corrugated surfaces. Gains of 10^4 in the efficiency of SHD from a silver grating with precisely controlled nanostructure are predicted theoretically and verified experimentally by high-resolution, angle-resolved SHD measurements. The investigation of SPP minigaps has demonstrated the critical role of selective enhancement when linear diffraction and SHD are used to probe the SPP dispersion relation. When linear diffraction is used, higher spatial harmonics can generate a pseudo-momentum gap, as demonstrated through a theoretical re-examination of recent experiments. When a minigap is probed by SHD, selective enhancement leads to enhanced normal- and backscattering which are signatures of localization--suggesting a more significant role for certain spatial harmonics in disordered systems. The sensitivity of selective enhancement to spatial harmonic composition has also been employed, through an innovative strategy, to probe the evolution of periodic metal deposition arising from photolysis of organometallics by an SPP-coupled, UV -laser beam. A rigorous electrodynamic model describing the deposition process has been developed, which includes important higher-order SPP interactions and allows demonstration of selective enhancement for probing SPP-enhanced photolysis.