The thesis describes the theoretical study of optical plasmons mediated light-matter interaction. We develop a finite element method to study spontaneous emission from emitters coupled to plasmonic waveguides. The numerical method is applied to calculate the coupling of a emitter coupled to a cylindrical nanowire, a square metallic nanowire and a metallic slot waveguide with inhomogenous dielectric environment. We also examine a quantum emitter coupled to optical nanoantennas. We mimic the conventional Yagi-Uda to realize its optical analogy for directional emission. We also propose a plasmon-based reconfigurable antenna to controllably distribute emission from a single emitter in spatially separated channels.