Active nanophotonic circuitry based on surface plasmons

Martin Thomaschewski

Research output: ThesisPh.D. thesis


This PhD thesis presents investigations of active plasmonic circuitry with high efficiencies
designed for compact and ultra-fast conversion of signals between the electrical
and optical domain. Owing to a strong field enhancement of electromagnetic fields
in metal nanostructures and a high field-overlap between the optical and electrostatic
fields, the presented plasmonic devices can serve as an alternative to traditional optical
telecommunication devices by offering faster device operation at much more compact
footprints. The experimental and theoretical studies consider nanophotonic waveguides
and couplers based on surface plasmon polaritons, which are collective electron oscillations
propagating along a metal-dielectric interface. The nanophotonic circuits are designed
and optimized by analytical and numerical methods, and subsequently fabricated
by electron-beam lithography and thin-film deposition techniques. The first part of the
thesis outlines the development of highly-dense integrated plasmonic circuits, which allow
the realization of branchless interferometric systems consisting of two parallel plasmonic
waveguides which are excited via ultra-compact antenna couplers. The thesis
continues with the development of active plasmonic structures, incorporating optoelectronic
phenomena for spin-selective photodetection and electro-optic modulation. The
device operation is characterized by their optical and optoelectronic response using optical
spectroscopy techniques, revealing a record-high electro-optic efficiency of the proposed
plasmonic modulator as compared with competitive devices based on the same
material platform. Further studies on utilizing long-range plasmonic waveguides suggests
the development of low-loss plasmonic electro-optic modulators. The thesis ultimately
arrives at the conclusion that active plasmonic technology can meet the future
needs of active integrated circuits and optical communications systems.
Original languageEnglish
Date of defence4. Sep 2020
Publication statusPublished - 2. Jun 2020


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