Energy-Efficient VCSELs For Optical Interconnects

This thesis addresses the intriguing topic of the quantum tunnelling of many-body systems such as Bose-Einstein condensates. The many-body process is built up from concurrently occurring single particle processes that are characterized by different momenta. Tunneling Dynamics in Open Ultracold Bosonic Systems The many-boson process exhibits exciting collective phenomena: the escaping particles fragment and lose their coherence with the source and among each other, whilst correlations build up within the system.

These methods are, therefore, of particular interest for experimental setups or technological applications.Besides zero-lag synchrony, group and cluster states are considered, enabling a description and study of complex synchronization patterns within the presented theory.

Selectivity in the Synthesis of Cyclic Sulfonamides DFT calculations were performed to attempt to shed light on the reaction sequence. Our efforts in this regard, specifically for the preparation of amino containing compounds incorporating an aromatic ring, are described in this doctoral thesis. This regioselective Heck reaction, combined with the reductive removal of the temporary amino-protecting group, allowed us to synthesize the Sceletium alkaloids: mesembrane, mesembranol and mesembrine.

By using a unique combination of iron catalyst and dichloride oxidant, various kind of naphthalene and phenanthrene derivatives were synthesized via annulation reaction with alkynes including direct C–H bond activation process. Iron-Catalyzed Synthesis of Fused Aromatic Compounds via C–H Bond Activation. This thesis describes the first practical example of iron catalysis in the carbon–hydrogen bond activation reaction to synthesized fused aromatic ring compounds. Iron catalysts in organic synthesis are strongly in demand because iron is non-toxic, inexpensive and the most abundant transition metal in the earth, although their use is still limited compared with that of rare, precious metals such as palladium, ruthenium and rhodium.

All chapters include insightful discussions and in-depth descriptions of the key principles of these new discoveries.

A key feature underlying the theoretical models is the unification of one-dimensional thermodynamic phase equilibria with film evolution phenomena in two- and three dimensions. Initially, an established 'phase portrait' method, useful for visualising and calculating phase equilibria of polymer-blend films, is generalised to systems without convenient simplifying symmetries.

In this thesis the static and dynamic properties of GaAs-based oxide-confined VCSELs emitting at 850 nm and 980 nm are analyzed and general rules for achieving energy-efficient data transmission using VCSELs at any wavelength are derived. Energy-efficient data communication is one of the most important fields in “Green Photonics” enabling higher bit rates at significantly reduced energy consumption per bit.

SPR spectroscopy is employed to study Au-based plasmonic nanostructures fabricated by novel methods, and a new experimental device is developed combining SPR with X-ray absorption spectroscopy at a synchrotron beamline.

Energy-Efficient VCSELs for Optical Interconnects These rules are verified in data transmission experiments leading to record energy-efficient data transmission across a wide range of multimode optical fiber distances and at high temperatures up to 85°C. Energy-efficient data communication is one of the most important fields in “Green Photonics” enabling higher bit rates at significantly reduced energy consumption per bit. Important trade-offs between energy efficiency, temperature stability, modulation bandwidth, low current-density operation and other VCSEL properties are revealed and discussed. In this thesis the static and dynamic properties of GaAs-based oxide-confined VCSELs emitting at 850 nm and 980 nm are analyzed and general rules for achieving energy-efficient data transmission using VCSELs at any wavelength are derived.

Using the new SPR-XAS setup developed in this work, the author has studied in-situ and real-time effects of X-ray irradiation in materials such as glasses and Co-phthalocyanines.. SPR spectroscopy is employed to study Au-based plasmonic nanostructures fabricated by novel methods, and a new experimental device is developed combining SPR with X-ray absorption spectroscopy at a synchrotron beamline. This work pursues a novel route to functionalizing large surfaces with hybrid nanoparticles.