Power electronic converter systems play an important role in the interconnection of renewable energy sources in microgrids and utility grid. The interface between energy sources and microgrids is usually implemented by digitally controlled power inverters. This thesis provides a…
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High power impulse magnetron sputtering (HiPIMS) is a plasma-based thin film deposition technique in which extremely high power pulses are applied to a conventional magnetron sputtering source. As a result, the plasma density in HiPIMS discharges is considerably increased up to …
With the more environmentally friendly smart grid initiatives during the past few years, intelligent operation and optimisation of the electricity distribution system have received an increasing attention in power system research worldwide. Power flow from the distribution subst…
Since the end of last century, power systems are more often operating under highly stressed and unpredictable conditions because of not only the market-oriented reform but also the rising of renewable generation and electric vehicles. The uncertain factors resulting from these c…
Wireless Sensor Networks (WSNs) use geographic routing to deliver measurement data to one or more sink nodes. In employing geographic routing, where data packets are forwarded along approximate geodesic (shortest) paths, WSNs can distribute the forwarding task unevenly between n…
The advent of modern railway signalling and train control technology allows the implementation of advanced real-time railway management. A number of researchers throughout the world have previously considered the problem of minimising the costs of train delays and have used vari…
In this thesis I report experimental studies toward developing versatile, compact, and reliable ultrafast sources in the 1.5 micron wavelength region, and their power scalability. The first part of the thesis reports on the development of a stable all-fiberized wavelength-tunabl…
Micro-Electro-Mechanical-Systems (MEMS) and especially physical sensors are part of a flourishing market ranging from consumer electronics to space applications. They have seen a great evolution throughout the last decades, and there is still considerable research effort for fur…
Light localization plays an important role in developing high resolution imaging and precision technologies in nanophotonics. In order to create and control nanoscale light localizations, this thesis has investigated into two research topics with different types of nanophotonic …
A new hyperspectral imaging technique and apparatus for imaging plasmon excitations and cathodoluminescence in nanostructures with nanoscale resolution have been developed. The apparatus, based on a scanning electron microscope synchronized with a multi-channel spectrum analyzer…
This thesis reports experimental indirect spectral transfer of shaped pulses from the near to mid-infrared via the use of an optical parametric oscillator. It was shown that good spectral fidelity of transfer can be achieved by making suitable adjustments to the OPO. The issues …
The aim of this thesis is to investigate the influence of ultraviolet laser light on single crystal lithium niobate surfaces with a focus on useful functionalisation. The investigations split naturally into three areas: effects on hydrophilicity by low intensity laser irradiatio…
This thesis reports on the progress made towards the integration of fibre optics components for the atom chip, a device developed to manipulate matter on the atomic scale for the purpose of quantum information processing, novel applications, and fundamental research. Following i…
This study investigates the broadcast/multicast authentication problems in wireless sensor networks (WSNs), particularly sensor nodes broadcast authentication and outside user authentication, and proposes efficient and secure solutions for them. The low cost and immunity from ca…
By their nature, scanning probe microscopy (SPM) measurements are ideally suited to the study of organic thin-film transistors (TFTs). In Chapter 3 surface potential measurements are made on TFTs made from the polymer pBTTT. The modification of the surface morphology by annealin…
Vibration-based energy harvesters transduce kinetic energy into electrical energy, which is then utilized to power small electronic systems, like wireless sensor nodes. Vibration-based harvesters are designed with high Q-factor to maximize their power generation capability; howe…
Optical fibre sensors have offered such unrivalled distributed sensing features that they continue to be successfully exploited in various industries for performing continuous measurements of the physical parameters, such as, temperature and strain. However, there arise certain …
Phase sensitive amplification (PSA) is a remarkably powerful tool if implemented correctly - it allows amplification with a noise figure lower than quantum mechanics normally dictates, and also allows the development of systems that coherently process the phase of their optical …
This thesis covers two areas of laser physics: optical cooling of rare-earth-doped solids by anti-Stokes fluorescence and the generation of pure Laguerre-Gaussian laser modes using a ring-shaped pump beam. A novel laser-based approach to determining local variations in the tempe…