This book presents several theoretical, numerical and experimental studies in the field of plasmonics, which I carried out during my PhD. One basic problem in plasmonics is the study of optical Bloch modes of planar arrays of metallic nanostructures. Here a new finite-elements-based numerical approach for the modal analysis of such structures is described. Then I present a thorough investigation of the optical properties of a well-known plasmonic crystal, which is the 1-D lamellar grating. The focus here is the possible use of this structure as a light trapping device for photovoltaics...