In terms of speed and bandwidth, photonic components are superior to their electronic counterparts. However, the diffraction limit has restricted downscaling of the conventional dielectric waveguides, where electromagnetic modes are confined to an optically dens core. Electromagnetic modes traveling along dielectric-metallic interfaces, known as surface plasmon polaritons (SPPs), have been proposed as a solution to the diffraction limit. Among possible plasmonic-based configurations, those which focus light into the dielectric core in a metal-insulator-metal (MIM) structure allow the manipulation and transmission of light at the nanoscale. In this thesis, first we develop an efficient method for designing the geometry of dielectric strip plasmonic structures, 2D generalizations for MIM structures, for future subwavelength wave-guiding applications. We formulate and solve the dielectric strip design optimization problem to ensure mono-mode propagation while balancing propagation losses and light confinement. Then, MIM-based Brag reflectors, photonic crystal and ring resonators, as building blocks of the future optical circuits, are presented and investigated. We show that compact MIM-based components may exhibit characteristics that are different from conventional dielectric optical components.