Three-dimensional full color light manipulation by plasmonic nanostructures

Using nanostructures to manipulate surface plasmon polariton (SPP) plane waves is an important issue. The interactions of surface nanostructure on SPP wave involve not only the in-plane behavior, but also out-of-plane scattering which is captured as the far-field radiated light. In this dissertation, by using the monochrome laser and multiwavlength laser, the three-dimensional focusing and diverging of SPP waves by a plasmonic structure composed of laser-fabricated gold nanobumps were studied. The forward and backward scattering from individual gold nanobump are observed above and below gold surface, respectively. The gold nanobump structure confers additional three-dimensional propagating wave vectors on SPP wave for departing from surface. A practical application to manipulate the three-dimensional plasmonic scattering is proposed by arranging the gold nanobumps. We manipulate the scattering of SPP waves by various plasmonic structures composed of arranged nanobumps on a gold thin film. Upon controlling the geometry of the plasmonic structures, the height, position, and pattern of scattered light can be modified as desired. It provides a simple and efficient way to project a specific light pattern into free space, and demonstrate the capability of three-dimensional light manipulation. By precisely designing a particular curved structure with appropriate radius of curvature and adjacent interspacing of nanobumps, we can construct a clear single focusing spot at a specific altitude. These results confirm the easy controllability of the focused spot in three-dimensional space by settling the unit curved structures. This research has potential to be applied in the area such as the integrated photonic circuit in the future.