A Review: Optical Second – Harmonic Generation Enhancement via Plasmonic Surface - Theory and Applications

Plasmonics has arisen as an interested research field in nanoscience and nanotechnology with many potential applications in fields ranging from bioscience, information processing and communication to quantum optics. It is based on the generation, manipulation and transfer of surface plasmons (SPs) that have the ability to manipulate light at the nanoscale. Realizing plasmonic applications requires comprehension how the SP-based properties depend on the nanostructures and how these properties can be controlled. Lately, significant attention has been devoted to the noteworthy and the comprehensions of nonlinear optical processes in plasmonic nanostructures, giving create to the new research field called nonlinear plasmonics. This review article gives a comprehensive understanding of physical mechanisms of one of these nonlinear optical processes, namely, second harmonic generation (SHG), with an focusing on the main differences with the linear response of plasmonic nanostructures. The main applications, ranging from the nonlinear optical characterization of nanostructure shapes to the optimization of laser beams at the nanoscale, are summarized and discussed. Future directions and developments, made possible by the unique combination of SHG surface sensitivity and field enhancements associated with surface plasmon resonances, are also addressed.