<p>This thesis describes the research I have done, and partly will do, during my time as a PhD student in the laboratory of Applied Optics at Linköping University. Due to circumstances beyond the scope of this book, this incorporates three quite different projects. The first two, involving gas sensing and measuring on paper with ellipsometry, have been discontinued, whereas the third one, measuring fluorescence with a computer screen and web camera, is in full progress and will be until I complete my studies.</p><p>Thus the purpose of this work also has several aspects. Partly, it describes performed research and its results, as well as theoretical background. On the other hand, it provides practical and theoretical background necessary for future work. While the three projects are truly quite different, each of them has certain things in common with each of the other. This is certainly also true for the necessary theory. Two of them involve spectroscopic ellipsometry, for example, while another pair needs knowledge of color theory, etc. This makes it impossible to separate the projects, despite of their differences. Hopefully, these links between the different projects, connecting the different chapters, will make this work whole and consistent in its own way.</p> / Report code: LiU-TEK-LIC-200 4-19. On the day of the public defence the status of article I was: In press and the status of article III was: Manuscript and has a new title. The old title was Computer screen photo-assisted spectroscopic fluorimetry.

Lead-tin telluride alloy, Pb1-xSnxTe, is a narrow band gap group IV–VI semiconductor with NaCl-like crystalline structure. This material has interesting electronic properties, which makes it suitable for designing infrared photo detectors, diode lasers, and thermo-photovoltaic energy converters. In this project, we used spectroscopic ellipsometry in the spectral range of 0.74–6.5 eV to probe the linear optical response of Pb1-xSnxTe alloys in terms of the complex dielectric function. A strong optical response in the range of 0.7-2.0 eV arising from optical absorption was found. We studied eleven different samples of Pb1-xSnxTe of p-type origin with x values in the range (0 ≤ x ≤ 1). They were prepared by means of molecular beam epitaxy (MBE) on BaF2 substrates with 15mm2 area.

I början 1980-talet publicerades en rapport – EKNA-rapport nr 8 - av Andersson &amp; Kärrqvist rörande elevers förklaringsmodeller inom optik. Rapporten studerade bl.a. förmågan hos elever i årskurserna 6 – 9 att använda abstrakta begrepp och förklaringar. Eftersom skolan sedan början av 1980-talet influerats av konstruktivistisk och socio-kulturell lärandeteori var vi intresserade av att se om detta påverkat elevers tänkande. Vår undersökning avser att med hjälp av en papper-och-penna-test bland elever i årskurserna 8 och 9 upprepa vissa delar av Andersson &amp; Kärrqvists undersökning, för att se om dagens elever uttrycker liknande förklaringsmodeller, och om vi kan spåra några tendenser till förändringar i fördelningen mellan konkreta och abstrakta förklaringar hos dagens elever jämfört med den tidigare undersökningen. Vårt resultat visar att de förklaringsmodeller som användes av eleverna i Andersson &amp; Kärrqvists undersökning i stor utsträckning förekommer även bland dagens elever. Vi tycker oss dock kunna se en ökad användning av abstrakta förklaringar jämfört med den tidigare undersökningen.

This thesis presents results of time-resolved photoluminescence experiments conducted on several different self-assembled InGaAs/GaAs and InAs/GaAs semiconductor quantum dot (QD) structures. Depending on the application in mind, different structural, electronic or optical properties have a different weight of importance. Fast carrier capture and relaxation is critical for QD based lasers, for example. In this thesis, the influence of surplus carriers, introduced through modulation-doping, is studied. It is shown that carrier capture is essentially unaffected whereas the intradot relaxation mechanisms, at least at low carrier concentrations, are fundamentally different. The phonon mediated cascade relaxation found in the undoped reference sample is replaced by efficient scattering with the built-in carriers in the case of the doped structures. Moreover, spin relaxation also depends on presence of extra carriers. During energy relaxation via carrier-carrier scattering, the spin polarization is preserved whereas in the undoped sample the strong interaction of relaxing carriers with LO phonons causes spin relaxation. The decay of the ground state spin polarization proceeds at the same rate for doped and undoped structures and is shown to be caused by acoustic phonons, even up to 300 K. While optimizing QD growth for specific applications, it is imperative to evaluate the influence of nonradiative recombination, which is most often detrimental. While misfit dislocations, deliberately introduced in the substrate, lead to the formation of laterally ordered, uniform dots, these samples are found to suffer from strong nonradiative recombination. Structures with different barrier thicknesses and numerical simulations indicate defects in the vicinity of the QDs as main origin of fast carrier trapping. On the other hand, it is shown that direct dot doping, compared to barrier doping or undoped structures, causes only minor degradation of the optical properties. Directly doped dots even exhibit a significantly weaker photoluminescence quenching with temperature, making them prospective for devices operating at room temperature. Finally, the superior proton radiation hardness of QD structures compared to quantum wells is demonstrated, which is due to the three-dimensional confinement. The increase of photoluminescence intensity at low to moderate doses is interpreted as an enhanced carrier transfer into the dots via the defects introduced into the material by the protons. / QC 20100920

In recent years, the use of alcohol and psychoactive drugs in combination withdriving has recieved increased attention. The lack of in-vehicle devices capable ofdetecting recent drug consumption and the difficulties associated with the breathbasedalcolocks in use today makes it interesting to investigate methods that areable to non-invasivelly measure analytes directly in the blood. The assignment of this project, commissioned by Volvo Technology Corporationand Volvo Car Corporation, is to map substances that constitute a possible threatto traffic safety, identify suitable detection markers as a proof of administrationof these substances, and study possible non-invasive techniques to detect thesemarkers. The objective is to present for Volvo if and how to continue evaluatingand developing a non-invasive detection device. The project has been carried out by performing an extensive literature study and averification experiment. From the literature review, a number of substances affectingdriving performance could be identified, and a metabolic study was performedfor each drug to map suitable biomarkers. Furthermore, two potential techniquesfor non-invasive detection, near-infrared Raman spectroscopy and near-infraredspectroscopy, were found and evaluated. The experiment was conducted usingnear-infrared Raman spectroscopy, with the aim of investigating the sensitivityand linearity of the method for ethanol detection. Based on the theoretical evaluation, both near-infrared Raman spectroscopy andnear-infrared spectroscopy are expected to have potential for non-invasive detectionof ethanol. The experiment further proved the theoretical conclusionsmade for near-infrared Raman spectroscopy. However, neither of the techniquesis thought to have potential for drug detection.Altogether, we believe that non-invasive ethanol detection is possible, but suggestfurther experiments in order to determine which technique to be preferred.

<p>Lead-tin telluride alloy, Pb1-xSnxTe, is a narrow band gap group IV–VI semiconductor with NaCl-like crystalline structure. This material has interesting electronic properties, which makes it suitable for designing infrared photo detectors, diode lasers, and thermo-photovoltaic energy converters. In this project, we used spectroscopic ellipsometry in the spectral range of 0.74–6.5 eV to probe the linear optical response of Pb1-xSnxTe alloys in terms of the complex dielectric function. A strong optical response in the range of 0.7-2.0 eV arising from optical absorption was found. We studied eleven different samples of Pb1-xSnxTe of p-type origin with x values in the range (0 ≤ x ≤ 1). They were prepared by means of molecular beam epitaxy (MBE) on BaF2 substrates with 15mm2 area.</p>

Potsdam, Universität, Thesis (doctoral), 2001.

Internet traffic has surpassed voice traffic and is dominating in transmission networks. The Internet Protocol (IP) is now being used to encapsulate various kinds of services. The new services have different requirements than the initial type of traffic that was carried by the Internet network and IP. Interactive services such as voice and video require paths than can guarantee some bandwidth level, minimum delay and jitter. In addition service providers need to be able to improve the performance of their networks by having an ability to steer the traffic along the less congested links or paths, thus balancing the load in a uniform way as a mechanism to provide differentiated service quality. This needs to be provided not only within their domains but also along paths that might traverse more than one domain. For this to be possible changes have been proposed and some are being applied to provide quality of service (QoS) and traffic engineering (TE) within and between domains. Because data networks now carry critical data and there are new technologies that enable providers to carry huge amount of traffic, it is important to have mechanisms to safeguard against failures that can render the network unavailable. In this thesis we propose and develop mechanisms to enable interdomain traffic engineering as well as to speed up the restoration time in optical transport networks. We propose a mechanism, called abstracted path information, that enable peering entities to exchange just enough information to engage in QoS and TE operations without divulging all the information about the internal design of the network. We also extend BGP to carry the abstracted information. Our simulations show that BGP could still deliver the same performance with the abstracted information. In this thesis we also develop a method of classifying failures of links or paths. To improve the restoration time we propose that common failures be classified and assigned error type numbers and we develop a mechanism for interlayer communication and faster processing of signalling messages that are used to carry notification signals. Additionally we develop a mechanism of exchanging the failure information between layers through the use of service primitives; that way we can speed up the restoration process. Finally we simulate the developed mechanism for a 24 node Pan American optical transport network. / <p>QC 20100913</p>

Zugl.: Erlangen, Nürnberg, Univ., Diss., 2005

Pädag. Hochsch., Diss., 2006--Heidelberg.