According to Bröstcancer förbundet, mammography is not efficient at detecting tumors in dense breast tissue or diagnosing breast cancer at its early stages. Ultrasound-optical tomography (UOT) is an imaging technique in development and has the potential for deep-tissue imaging. If ultrasound-optical tomography were implemented, it would be easier to differentiate between malignant, benign, and healthy tissue from any type of breast tissue. UOT is an imaging technique that takes advantage of high penetration depth and high spatial resolution of ultrasound imaging and optical imaging. In UOT, a laser light and an ultrasound pulse propagate through the tissue simultaneously at a frequency f$_L$ and f$_{US}$, respectively. The light will scatter while it propagates through the tissue and some of this scattered light will become frequency shifted by ultrasound pulse due to the acousto-optic effect. The tagged light will have the frequency $f_T = f_L + f_{US}$. The tagged (frequency shifted) light can be separated from the untagged light (unshifted light) using a thulium-doped lithium niobate, Tm$^{3+}$:$~$LiNbO$_3$, crystal as a filter. The crystal is kept at a temperature close to zero kelvin because then it exhibits unique characteristics, e.g. it has a narrow linewidth and long-lived hyperfine levels at this temperature. The filter is created by a method known as spectral hole burning (SHB). A laser beam is used to transfer electrons from the ground state to the excited state to create a hole at a specific wavelength. The spectral hole is created at the frequency of the tagged light and hence a narrow bandpass filter is constructed inside the crystal. The tagged light is fully transmitted through the filter while it highly attenuates untagged light. The tagged light is detected with a photodiode and processed in MATLAB after it has been transferred to an oscilloscope. This thesis aims to model and design a phantom probe that minimizes vibration and other unwanted movements or disturbances during measurements. The automated phantom holder will be used for the recording of 3D images. Another task of the thesis was to obtain the absorption spectrum of a 0.005$\%$ Tm$^{3+}$:$~$LiNbO$_3$ crystal when it is cooled down to 3$~$K to ensure that the crystal has the same absorption characteristics as predicted in literature. The absorption line at $\sim$ 800$~$nm is of interest since oxyhemoglobin and deoxyhemoglobin have similar absorption coefficients at $\sim$ 800$~$nm. Optical absorption and scattering information will help determine if the sample contains a cancerous region. The phantom probe was modeled in Solid Works and manufactured through 3D printing. In this setup, the sample holder was chosen to be translated while the ultrasound transducer was stationary to generate less blurry images. The design of the probe has to accommodate two detection schemes, reflection and transmission mode. The phantom probe was automated using a linear servo actuator since it was controlled with pulse-width modulation (PWM). It used a square signal as an input that could be generated with an Arbitrary signal generator (AWG). Using a device that operates with a signal was important because it would make it easier to integrate it into the experimental setup. The whole phantom probe was constructed in a cost-efficient way and in a way that it could be easily incorporated into the experimental setup. The absorption spectrum showed that the crystal has an absorption line at $\sim$ 794.3$~$nm. This absorption spectrum was compared to an absorption spectrum taken at 8$~$K on the same crystal and captured with a different method. Both absorption spectra had the same absorption peaks at almost the same wavelengths but they also showed few discrepancies that may depend on the temperature difference and the recording method. In this thesis, the absorption spectrum data taken was captured by sweeping the wavelength. The signal was captured with a photodiode, transferred to an oscilloscope, and then processed in MATLAB. The absorption spectrum data at 8$~$K was obtained using a Fourier transform spectrometer, resulting in data with little noise and well resolved peaks. To conclude, a functional and robust phantom probe was designed and manufactured that could withstand vibration and other undesired movements. An absorption spectrum of Tm$^{3+}$:$~$LiNbO$_3$ crystal was obtained at 3$~$K and compared to absorption taken at 8$~$K and compared to literature and previous measurements under similar conditions.

Plasmonic effects in nanosized particles enhance the interaction between light and matter due to the localized surface plasmon resonance, with potential applications such as all-optical transistors and optical computers. Commonly, the dynamics of nanoparticles’ optical properties are assessed via pump-probe spectroscopy, where a plasmonic structure is exited by an initial laser, the pump. Thereafter a second, less intense laser, a probe, interacts with the now excited structure at a time delay. Through measurements of the probelight transmitted by the matter, the optical dynamics of the structure are monitored. Similar methodologies can potentially be used for other applications as well, such as all-optical switching. This study focuses on an implementation of a numerical finite element method model simulating a pump-probe experiment to predict the effects of different geometries and evaluate experimental data. The simulations are split into three parts. Initially, periodically spaced nanoparticles are excited by the pump laser. Then the model estimates the internal thermal dynamics of the excited nanoparticles and in turn, determines the change in complex permittivity. Lastly, the probe-matter interaction is modeled. To evaluate the model, a comparison with another model was performed. Furthermore, simulations of periodically spaced gold dimer nanoparticles in air were done to investigate how dimers affect transmitted light. For a probe light polarization rotated 45◦ against the axis parallel to the dimer, a change in rotation of 6◦ over 35 fs was induced by the pump, indicating a potential switching mechanism.

This licentiate thesis concerns topics in non-interacting and interacting quantum physics in one dimension. We present the notions of Wannier functions and tight-binding models. Quantum walks are discussed, quantum mechanical analogues to random walks. We demonstrate the ideas of Bloch oscillation and super-Bloch oscillation - revivals of quantum states for particles in a periodic lattice subject to a constant force. Next, the Rabi model of light-matter interaction is derived. The concept of quantum phase transitions is presented for the Dicke model of superradiance. The idea of adiabatic elimination is used to highlight the connectedness of the Dicke model. Finally, we present a one-dimensional interacting system of resonators and artificial atoms that could be built as a superconducting circuit. Using adiabatic elimination as well as matrix product states, we find the phase diagram of this model.

The aim of this study is to study the ground-state of various elements including Hydrogen molecules and Heliumatoms using a self written Density Functional Theory code. We limit ourselves to simple linear moleculesusing cylindrical symmetry, for which the computational difficulty is manageable and appropriate for anundergraduate thesis. We focus on the binding length and energy of the molecules stated here. Charge densityis calculated using the Poisson equation, which is used to calculate the potential and correlation potential. From the distance dependent of the total energy, the chemical bond length can be determined. The results showa total energy for a Hydrogen molecule is -31.3 eV and most optimal binding length is identified at 0.76 Å.

The present master's thesis deals with numerical modeling of solid-state micrometrical-sized polymeric dye lasers, commonly denoted as microcavities. It is part of a large research initiative carried out in the optics group, at the MAP (Microelectronics and Applied Physics) department in KTH (Kungliga Tekniska Högskolan - Royal Technical School) and targeted towards the design and manufacturing of micro- and nano-scaled polymeric components for nano-photonics, primarily lasers. The finite element method (FEM) in frequency domain is used as a primary modeling tool through the simulation software COMSOL Multiphysics. Models for spontaneous emission, optical losses and gain are developed and demonstrated. A specic layout is studied: the double hexagonal microcavity. While it was expected to be a good candidate for a laser, the design shows unexpected properties making it useful for sensing applications. Finally, the transposition of models to time domain is initiated : a replacement solution for the lacking perfectly matched layer (PML) in Comsol is developed and demonstrated. Methods for modeling materials parameters in time domain are investigated, together with the possible use of a more suitable algorithm : finite dierences in time domain (FDTD) or Yee's scheme.

This thesis deals with experimental studies of electron transfer reactions between oppositely charged ions (mutual neutralisation). These were performed at the unique double electrostatic ion storage ring DESIREE at Stockholm University, which was put into full operation in 2017. In the first two published articles of this thesis, two atmospheric collision systems are treated, namely O+/O−  and N+/O−. The aim was to reproduce previous published results from a single-pass (non-stored) merged ion beams setup in UCLouvain (Belgium) and thus provide a measure of DESIREE’s capacity and resolution. In addition, the effects of metastable ions were investigated with the support of theoretical calculations. The third published paper of this thesis deals with collisions between I+ and I− (iodine ions), a process relevant to electric thrusters for new spacecraft. The results are compared with theoretical calculations in order to provide an understanding of how the reaction takes place. Preliminary results on electron transfer reactions between diatomic molecules and atoms are presented.

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. 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.</p>

This thesis contains the results of research on the spectral control of lasers, specifically, the thermal limitations of volume Bragg gratings (VBGs), employed as laser-cavity end mirrors. The investigations consisted of both experiments and numerical simulations. For the experiments, a diode-pumped Yb:KYW laser with a VBG that had an absorption coefficient of 2.8% cm-1, in the 1 μm spectral region, was constructed. The computer model comprised of a transfer-matrix model and a three-dimensional, finite element model, working together. The absorption of the reflected laser beam changed the reflecting properties of the VBG, which affected the laser’s stability and other performances. The primary effect was a broadening of the grating spectrum accompanied by decreased diffraction efficiency. The reduced reflectivity lead to a leakage of the radiation through the grating during lasing. Both the experiments and the simulations showed that the laser became successively more unstable when the power was increased. Also, the simulations showed that this increased sensitivity was due to a reshaping of the intensity distribution profile inside the grating, which, in turn, lead to a sharp reduction of the diffraction efficiency. For circulating powers above this limit, the laser output rolled off and the power was instead leaking out through the VBG. Furthermore, the simulations also showed that the power limit was highly dependent on the length of the employed VBG. For instance, a 2 mm long VBG could withstand approximately 9.5 times higher incident power than a 10 mm long one could. Also, it was found that the limit, expressed in the terms of the incident power, related approximately linearly to the size of the beam radius. / Denna licentiatavhandling innehåller forskningsresultat som behandlar spektral kontroll av lasrar, specifikt genom volymbraggitters (VBG) termiska begränsningar, då de används som speglar i laserkaviteter. Undersökningarna bestod av både experiment och simuleringar. För experimenten konstruerades en diod-pumpad Yb:KYW laser med ett VBG som hade en absorptionskoefficient på 2,8% cm-1, i våglängdsområdet kring en mikrometer. Datormodellen innefattade en modell av gitterstrukturen baserad på överföringsmatriser och en tredimensionell modell baserad på finita elementmetoden, för beräkning av värme-fördelningen. Absorption av den reflekterade laserstrålen ändrade volymbraggittrets reflekterande egenskaper, vilket i sin tur påverkade laserns stabilitet och dess prestanda. De huvudsakliga effekterna var en breddning av gittrets spektra och en minskad diffraktionsverkningsgrad. Både experimenten och simuleringarna visade att en laser blir successivt mer instabil när den optiska effekten ökar. Simuleringarna visade även att den ökade känsligheten berodde på en förändring av intensitetsfördelningen inuti gittret, vilket accelererade reduktionen av gittrets reflekterande förmåga. Uttryckt i mot gittret infallande effekt, har lasern en tydlig övre effektgräns. När den gränsen har uppnåtts leder vidare ökning av pumpeffekten i huvudsak till ökat läckage genom volymbraggittret, och inte till ökad uteffekt hos laserstrålen. Vidare visade simuleringarna också att en lasers effektgräns är starkt beroende av längden på det använda volymbraggittret. Till exempel tålde ett 2 mm långt gitter cirka 9,5 gånger högre infallande effekt än ett 10 mm långt gitter. Dessutom visade det sig att effektgränsen, uttryckt i infallande effekt, berodde approximativt linjärt på strålradiens storlek. / <p>QC 20130507</p>

Zahlreiche Geräte, die in den Naturwissenschaen, in der Industrie und im Gesundheitswesen unverzichtbar sind, basieren auf Strahlen schneller geladener Teilchen. Dazu zählen unter anderem Elektronen- und Ionenmikroskope, entsprechende Lithographiestrahlanlagen und Röntgenstrahlungsquellen. Magnetische Optiken, die Strahlen geladener Teilchen ablenken, formen und fokussieren, sind das Rückgrat aller Geräte die mit hochenergetischen Teilchen arbeiten, da sie im Vergleich zu Optiken, die auf elektrischen Feldern basieren, bei hohen Teilchengeschwindigkeiten eine überlegene optische Leistung aufweisen. Konventionelle makroskopische magnetische Optiken sind jedoch groß, teuer und platzraubend, nicht hochfrequenzfähig und erfordern aktive (Wasser-)Kühlung zur Wärmeabfuhr. Sie sind daher für Mehrstrahlinstrumente, miniaturisierte Anwendungen und schnelle Strahlmanipulation ungeeignet, die für zukünftige Fortschritte in der Nanofabrikation und -analyse gebraucht werden. Im Rahmen dieser Arbeit wurden die ersten magnetischen selbst-assemblierenden Mikro-Origami-Elektronenoptiken entwickelt, hergestellt und charakterisiert. Mit dem verwendeten Miniaturisierungsansatz können, bei ähnlicher optischer Leistung, alle oben genannten Nachteile von konventionellen magnetischen Optiken überwunden werden. Die außergewöhnlichen Eigenschaften dieser optischen Elemente werden durch die einzigartigen Merkmale der Mikrospulen ermöglicht: geringe Größe, geringe Induktivität und geringer Widerstand. Im Rahmen dieser Arbeit wurden unter anderem adaptive Phasenplaen hergestellt, die Elektronenvortexstrahlen mit einem bislang unerreichten Bahndrehimpuls von bis zu mehreren 1000 ̄h erzeugen. Des Weiteren wurden schnelle Elektronenstrahldeflektoren zur Strahlablenkung, zum zweidimensionalen Rastern und für stroboskopische Experimente gefertigt. Sie besitzen eine Ablenkleistung im mrad-Bereich für 300 kV Elektronen und einen Frequenzdurchgang bis zu 100 MHz. Darüber hinaus wurden miniaturisierte adrupollinsen mit Brennweiten kleiner als 46 mm für 300 kV Elektronen entwickelt. Diese drei Arten elektronenoptischer Elemente sind von großem Interesse für verschiedenste Anwendungen in der Nanofabrikation und -analyse, da sie unter anderem als integrale Bestandteile von zu entwickelnden Mehrstrahlinstrumenten, miniaturisierten Geräten und stroboskopischen Messaufbauten dienen können.:1 Introduction 1.1 Charged Particle Optics 1.2 Miniaturized Charged Particle Optics 1.3 Phase Plates for Transmission Electron Microscopy 2 Charged Particle Optics 2.1 Hamiltonian Formalism 2.2 Gaussian Matrix Optics 2.3 Transfer Matrices of Magnetic Elements 2.3.1 Single Quadrupole 2.3.2 Quadrupole Multiplets 2.3.2.1 Quadrupole Doublet 2.3.2.2 Quadrupole Triplet 2.3.2.3 Higher Order Quadrupole Multiplets 2.4 Scaling Laws for Charged Particle Optics 2.4.1 Thin Film 2.4.2 Electrostatic Scaling Laws 2.4.3 Magnetic Scaling Laws 3 Design and Fabrication of Miniaturized Electron Optics 3.1 Basics of Polymer-Based Self-Assembly Technology 3.2 Basic Coil Design and Magnetic Field Simulations 3.3 CoFeSiB-Pyrex Core-Shell Micro Wires 3.4 Fabrication of Self-Assembled Micro Coil Devices 4 Optical Properties of Self-Assembled Miniaturized Electron Optics 4.1 Electron Vortex Phase Plate 4.1.1 Projected Magnetic Fields 4.1.2 Vortex Beam Characteristics 4.2 Miniaturized Deflector 4.3 Quadrupole Focusing Optic 4.4 High Frequency Characteristics of Self-Assembled Electron Optics 5 Summary and Outlook 5.1 Applications of Electron Vortex Beams with Large OAM 5.2 Optics of Large Optical Power for Pulsed Instruments 5.3 Stroboscopic TEM Measurements 5.4 Miniaturized Wigglers, Undulators and Free Electron Lasers 5.5 Towards Integrated Electron Optical Systems / Beams of highly accelerated charged particles are essential for numerous indispensable devices used throughout natural sciences, industry and the healthcare sector, e.g., electron and ion microscopes, charged particle lithography machines and X-ray radiation sources. Magnetic charged particle optics that deflect, shape and focus high-energy charged particles are the backbone of all such devices, because of their superior optical power compared to electric field optics at large particle velocities. Conventional macroscopic magnetic optics, however, are large, costly and bulky, not high frequency capable and require active cooling for heat dissipation. They are therefore unsuitable for fast beam manipulation, multibeam instrumentation, and miniaturized applications, much desired for future advances in nanofabrication and analysis. The first on-chip micro-sized magnetic charged particle optics realized via a self-assembling micro-origami process were designed, fabricated and characterized within the frame of this work. The utilized micro-miniaturization approach overcomes all the aforementioned obstacles for conventional magnetic optics, while maintaining similar optical power. The exceptional properties of these optical elements are rendered possible by the unique features of strain-engineered micro-coils: small size, small inductance and small resistivity. Within the frame of this work, adaptive phase plates were fabricated, which generate electron vortex beams with an unprecedented orbital angular momentum of up to several 1000 ̄h. Furthermore, fast electron beam deflectors for beam blanking, two-dimensional scanning and stroboscopic experiments were manufactured. They possess a deflection power in the mrad regime for 300 kV electrons and a high frequency passband up to 100 MHz. Additionally, miniaturized strong quadrupole lenses with focal lengths down to 46 mm for 300 kV electrons have been developed. These three types of electron optical elements are of great interest for a wide range of applications in nanofabrication and analysis, as they serve as integral components of future multibeam instruments, miniaturized devices, and stroboscopic measurement setups to be developed.:1 Introduction 1.1 Charged Particle Optics 1.2 Miniaturized Charged Particle Optics 1.3 Phase Plates for Transmission Electron Microscopy 2 Charged Particle Optics 2.1 Hamiltonian Formalism 2.2 Gaussian Matrix Optics 2.3 Transfer Matrices of Magnetic Elements 2.3.1 Single Quadrupole 2.3.2 Quadrupole Multiplets 2.3.2.1 Quadrupole Doublet 2.3.2.2 Quadrupole Triplet 2.3.2.3 Higher Order Quadrupole Multiplets 2.4 Scaling Laws for Charged Particle Optics 2.4.1 Thin Film 2.4.2 Electrostatic Scaling Laws 2.4.3 Magnetic Scaling Laws 3 Design and Fabrication of Miniaturized Electron Optics 3.1 Basics of Polymer-Based Self-Assembly Technology 3.2 Basic Coil Design and Magnetic Field Simulations 3.3 CoFeSiB-Pyrex Core-Shell Micro Wires 3.4 Fabrication of Self-Assembled Micro Coil Devices 4 Optical Properties of Self-Assembled Miniaturized Electron Optics 4.1 Electron Vortex Phase Plate 4.1.1 Projected Magnetic Fields 4.1.2 Vortex Beam Characteristics 4.2 Miniaturized Deflector 4.3 Quadrupole Focusing Optic 4.4 High Frequency Characteristics of Self-Assembled Electron Optics 5 Summary and Outlook 5.1 Applications of Electron Vortex Beams with Large OAM 5.2 Optics of Large Optical Power for Pulsed Instruments 5.3 Stroboscopic TEM Measurements 5.4 Miniaturized Wigglers, Undulators and Free Electron Lasers 5.5 Towards Integrated Electron Optical Systems

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