Development of Chiral Plasmonic Devices and Advanced Deposition Techniques with Focused Charged Particle Beams

This work focuses on chiral plasmonic structures for controlling the polarization of light on the nanoscale. Plasmonics is beneficial for this purpose; at its foundation are collective electron oscillations that can couple with light and concentrate it below the diffraction limit. Recent advances in direct writing with focused electron and ion beams allow for the precise fabrication of three-dimensional plasmonic structures. First, plasmonic double helices are presented as broadband antennas for circularly polarized light. They exhibit a strong chiroptical interaction with a high dissymmetry factor in the visible range as well as directional emission and are also suitable for coupling to quantum emitters. Subsequently, a novel polarization transducer is described: A plasmonic two-wire line coupled to a double-helix antenna via an adiabatic transition region. This device converts linear polarization to circular polarization and offers a compact, on-chip alternative to traditional optical components. Additionally, a maskless technique was developed for area-selective gold deposition. Electron beam-induced dissociation of a gold compound creates an autocatalytically active gold seed layer that enables gold growth at low temperatures on complex topographies. Additionally, this effect enables precise measurement of local temperature changes via 3D electron beam writing. Thus, this work combines plasmonics and materials science, demonstrating its potential for miniaturized photonic systems.