In this project, the fabrication of single-photon detectors based on superconducting nanowires is presented, with great focus on extending their operation range to the mid infrared. In particular, Niobium Titanium Nitride (NbTiN) and Molybdenum Silicide (MoSi), superconducting materials with different properties, are presented, studied and used as fabrication platforms. Different approaches are followed, mainly adjusting the nanowire width and thickness to achieve near unity quantum efficiency at mid infrared wavelengths. With the vision of using these devices for atmospheric LIDAR and sensing experiments, saturation at 2050 nm is studied that corresponds to the absorption peak of CO2. For the best device made on NbTiN thin films, unity quantum efficiency is shown at 2050 nm with a time jitter of 116 ps at 1550 nm. Simulations using the transfer matrix method and the commercial software Lumerical are carried out, concluding that the devices made in NbTiN could have 23.1-26.7% system detection efficiency at 2050 nm on a Silicon SiO2/Si platform. Further improvements show that the detection efficiency could reach between 52-62% (for 0.33 and 0.5 fill factor, respectively calculated with FDTD simulations) by engineering optical cavities. / I detta projekt presenteras en fabrikations process för enstaka foton detektorer baserade på supraledande nanotrådar. Fokuset har legat på att utöka våglängds regionen där detektorernas kan detektera till mid-infrarött ljus. Två specifika supraledande material, Niobium Titan (NbTiN) och Molybdenum Silicide (MoSi), med olika egenskaper har studerats och använts som material. Dimensionerna på nanotrådarna, framför allt tjockleken och bredden, har optimerats för att uppnå nära enhetlig kvant-effektivitet vid mid-infraröda våglängder. Med visionen att detektorerna ska användas för atmosfäriska LiDAR mätningar har de studerats för satruering vid 2050 nm som motsvarar ett absorbtions maximum för CO2. Detektorerna tillverkade med NbTinN uppnådde 100% kvant effektivitet för 2050 nm ljus med ett tids jitter på 116 ps vid 1550 nm ljus. Simuleringar med överförings matrisen metoden och den kommersiella mjukvaran Lumerical visar att NbTiN detektorer placerade på en SiO2/Si platform kan ha en 23.1-26.7% effektivitet vid 2050 nm. Ytterligare simuleringas visar att effektiviteten kan nå upp till 52-62% (för 0.33 och 0.5 fyllnadsfaktor, respektive beräknad med FDTD) genom att inkludera optiska kaviteter.

Using shallow implantation of ions and molecules with masses centred at 27 atomic mass units(amu) in diamond, a new artificial optical centre with unique properties has been created. The centre shows a linearly polarised fluorescence with a main narrow emission line mostly found at 582 nm, together with a weak vibronic sideband at room temperature. The fluorescence lifetime is∼2 ns and the brightest centres are more than three times brighter than the nitrogen-vacancy centres. A majority of the centres shows stable fluorescence whereas some others present a blinking behaviour, at faster or slower rates. Furthermore, a second kind of optical centre has been simultaneously created in the same diamond sample, within the same ion implantation run. This centre has a narrow zero-phonon line (ZPL) at∼546 nm and a broad phonon sideband at room temperature. Interestingly, optically detected magnetic resonance (ODMR) has been measured on several single 546 nm centres and two resonance peaks are found at 0.99 and 1.27 GHz. In view of their very similar ODMR and optical spectra, the 546 nm centre is likely to coincide with the ST1 centre, reported once (with a ZPL at 550 nm), but of still unknown nature. These new kinds of centres are promising for quantum information processing, sub-diffraction optical imaging or use as single-photon sources.

In recent years, the usage of 3D deep learning techniques has seen a surge,mainly driven by advancements in autonomous driving and medical applications.This thesis investigates the applicability of existing state-of-the-art 3Ddeep learning network architectures to dense voxel grids from single photoncounting 3D LiDAR. This work also examine the choice of loss function asa means of dealing with extreme data imbalance, in order to segment peopleand vehicles in outdoor forest scenes. Due to data similarities with volumetricmedical data, such as computer tomography scans, this thesis investigates ifa model for 3D deep learning used for medical applications, the commonlyused 3D U-Net, can be used for photon counting data. The results showthat segmentation of people and vehicles is possible in this type of data butthat performance depends on the segmentation task, light conditions, and theloss function. For people segmentation the final models are able to predictall targets, but with a significant amount of false positives, something that islikely caused by similar LiDAR responses between people and tree trunks.For vehicle detection, the results are more inconsistent and varies greatlybetween different loss functions as well as the position and orientation of thevehicles. Overall, we consider the 3D U-Net model a successful proof-ofconceptregarding the applicability of 3D deep learning techniques to this kindof data. / Under de senaste åren har användningen för djupinlärningstekniker för 3Dsett en kraftig ökning, främst driven av framsteg inom autonoma fordon ochmedicinska tillämpningar. Denna avhandling undersöker befintliga modernadjupinlärningsnätverk för 3D i täta voxelgriddar från fotonräknande 3D LiDARför att segmentera människor och fordon i skogsscener. Vidare undersöksvalet av målfunktion som ett sätt att hantera extrem dataobalans. På grundav datalikheter med volymetriska medicinska data, såsom datortomografi,kommer denna avhandling att undersöka om en modell för 3D-djupinlärningsom används för medicinska applikationer, nämligen 3D U-Net, kan användasför fotonräknande data. Resultaten visar att segmentering av människor ochfordon är möjligt men att prestanda varier avsevärt med segmenteringsuppgiften,ljusförhållanden, och målfunktioner. För segmentering av människorkan de slutgiltiga modellerna segmentera alla mål men med en betydandemängd falska utslag, något som sannolikt orsakas av liknande LiDAR-svarmellan människor och trädstammar. För segmentering av fordon är resultatenmer oberäkneliga och varierar kraftigt mellan olika målfunktioner såväl somfordonens position och orientering. Sammantaget anser vi att 3D U-Netmodellenvisar på en framgångsrik konceptvalidering när det gäller tillämpningav djupinlärningstekniker för 3D på denna typ av data.

Superconducting nanowire single-photon detectors are the most promising technology in quantum photon information. They offer high speed, high detection efficiency, low dark count rate as well as low timing jitter compared to other single photon detection solutions. Since the recent advances in photonic quantum computing, the drive for improvement of the implementation complexity, performance and scalability of quantum photon detection has increased. This presents challenges with the current device readout schemes and alternative solutions are required. One of the key parameters to improve the scalability of superconducting nanowire single-photon detectors, is reducing the power dissipation per pixel. This is especially important in cryogenic readouts, where the performance of electronic components changes compared to room temperature. Moreover, the performance of a cryogenic superconducting nanowire single-photon detector readout is dependent both on the device and readout electronics level characteristics, and both must be fine-tuned for desired performance. A solution to the scalability of superconducting nanowire single-photon detectors (SNSPDs) is the development of a readout scheme with minimized power dissipation. We propose a fully digital readout scheme interfaced with a superconducting nanowire single-photon detector (SNSPD), that allows photon detection and reset. For this purpose, a digital single-pixel SiGe Bi-CMOS readout is designed, simulated, and characterised. An improved readout scheme is proposed with an addition of a die resistor to allow a full reset of the detector. / Supraledande nanotrådsdetektorer baserade på enstaka fotoner är ett av de mest avancerade koncepten inom kvantfotoninformationsteknik. Syftet med att utveckla denna teknik är att förbättra egenskaper så som komplexiteten, prestandan och skalbarheten. En av de viktigaste parametrarna för att förbättra skalbarheten hos supraledande nanotrådsdetektorer med enstaka fotoner är att minska energiförbrukningen per pixel. Detta är särskilt viktigt i kryogena avläsningar, där prestandan hos elektroniska komponenter förändras jämfört med rumstemperatur. Dessutom, beror prestandan hos en kryogen supraledande nanotrådsdetektor både på komponenten och på avläsningselektroniken,och båda måste finjusteras för att uppnå önskad prestanda. En lösning på kalbarheten för supraledande nanotrådsdetektorer med enstaka fotoner (SNSPDs) är att realisera avläsning med minimerad effektförlust. Vi föreslår en helt digital avläsning som är kopplad till en supraledande enfoton nanotrådsdetektor (SNSPD), som gör det möjligt att detektera fotoner och att återställa detektorn efter avläsning. För detta ändamål, designades, simuleras och karakteriserades en digital avläsningkrets med en enda pixel. Ett förbättrat avläsningssystem föreslås genom att lägga till ett diskret motstånd för att möjliggöra en fullständig återställning av detektorn.

No description available.

[pt] Neste trabalho são apresentados dois reflectômetros ópticos por contagem de fótons no domínio do tempo para o monitoramento de fibras ópticas. O primeiro foi projetado para obter faixas dinâmicas altas. Demonstrou-se a sua capacidade de sintonização no monitoramento de redes passivas WDM-PON durante o tráfego de dados. 32 dB de faixa dinâmica com 6 m de resolução foram atingidos. O segundo reflectômetro foi projetado para atingir resoluções ultra altas. As aplicações neste caso, além do monitoramento de uma rede TDM-PON de curto alcance, foram na caracterização de redes de Bragg dispersivas e na descrição e modelagem de um fenômeno não reportado antes na literatura, chamado nesta tese de reflexão por curvatura. Foi demonstrada uma resolução menor que 3 cm com faixa dinâmica maior que 14.0 dB. / [en] This thesis presents the development of two photon counting optical time domain reflectometers for fiber optic links monitoring. The first one was focused on high dynamic range. It is demonstrated its tunable capability for a WDM-PON in-service monitoring. 32 dB on dynamic range and a two-point resolution of 6 m is achieved. The second reflectometer was design to accomplish an ultra high resolution. The monitoring of a short TDM-PON is performed. Moreover, due to its high resolution, a chirped fiber Bragg grating is characterized and a non previous reported phenomena, the bend reflection, is shaped and described. It is demonstrated 3 cm two-point resolution and more than 14 dB on dynamic range.

Vision has always been one of the most important cognitive tools of human beings. In this regard, the development of image sensors opens up the potential to view objects that our eyes cannot see. One of the most promising capability in some image sensors is their single-photon sensitivity that provides information at the ultimate fundamental limit of light. Time-resolved single-photon avalanche diode (SPAD) image sensors bring a new dimension as they measure the arrival time of incident photons with a precision in the order of hundred picoseconds. In addition to this characteristic, they can be fabricated in complementary metal-oxide-semiconductor (CMOS) technology enabling the integration of complex signal processing blocks at the pixel level. These unique features made CMOS SPAD sensors a prime candidate for a broad spectrum of applications. This thesis is dedicated to the optimization and characterization of quantum imagers based on the SPADs as part of the E.U. funded SUPERTWIN project to surpass the fundamental diffraction limit known as the Rayleigh limit by exploiting the spatio-temporal correlation of entangled photons. The first characterized sensor is a 32×32-pixel SPAD array, named “SuperEllen”, with in-pixel time-to-digital converters (TDC) that measure the spatial cross-correlation functions of a flux of entangled photons. Each pixel features 19.48% fill-factor (FF) in 44.64-μm pitch fabricated in a 150-nm CMOS standard technology. The sensor is fully characterized in several electro-optical experiments, in order to be used in quantum imaging measurements. Moreover, the chip is calibrated in terms of coincidence detection achieving the minimal coincidence window determined by the SPAD jitter. The second developed sensor in the context of SUPERTWIN project is a 224×272-pixel SPAD-based array called “SuperAlice”, a multi-functional image sensor fabricated in a 110-nm CMOS image sensor technology. SuperAlice can operate in multiple modes (time-resolving or photon counting or binary imaging mode). Thanks to the digital intrinsic nature of SPAD imagers, they have an inherent capability to achieve a high frame rate. However, running at high frame rate means high I/O power consumption and thus inefficient handling of the generated data, as SPAD arrays are employed for low light applications in which data are very sparse over time and space. Here, we present three zero-suppression mechanisms to increase the frame rate without adversely affecting power consumption. A row-skipping mechanism that is implemented in both SuperEllen and SuperAlice detects the absence of SPAD activity in a row to increase the duty cycle. A current-based mechanism implemented in SuperEllen ignores reading out a full frame when the number of triggered pixels is less than a user-defined value. A different zero-suppression technique is developed in the SuperAlice chip that is based on jumping through the non-zero pixels within one row. The acquisition of TDC-based SPAD imagers can be speeded up further by storing and processing events inside the chip without the need to read out all data. An on-chip histogramming architecture based on analog counters is developed in a 150-nm CMOS standard technology. The test structure is a 16-bin histogram with 9 bit depth for each bin. SPAD technology demonstrates its capability in other applications such as automotive that demands high dynamic range (HDR) imaging. We proposed two methods based on processing photon arrival times to create HDR images. The proposed methods are validated experimentally with SuperEllen obtaining >130 dB dynamic range within 30 ms of integration time and can be further extended by using a timestamping mechanism with a higher resolution.

La scintillation organique correspond au phénomène d’émission de lumière par un matériau moléculaire à la suite de l’excitation de celui-ci par un rayonnement externe d’énergie donnée. Lors de l’interaction, le dépôt d’énergie induit des transitions électroniques peuplant des états dont la plupart se désexcite de manière non radiative, à l’exception d’une, entre le premier état électronique singulet et l’état fondamental de la molécule. Lors de cette relaxation, un photon de fluorescence est émis. Cette émission a deux origines : i) l’excitation directe par le rayonnement primaire et les électrons secondaires ; elle donne lieu à une émission dite rapide ou prompte ; ii) l’ionisation par le rayonnement primaire et les électrons secondaires ; elle donne lieu à une émission dite lente ou différée. Ce travail de recherche fondamentale, à la fois théorique et expérimental, fait l’analyse de toutes les étapes du processus, de l’interaction primaire à l’émission de fluorescence, de manière à relier la dose déposée à la quantité de lumière émise, à des fins d’applications en dosimétrie médicale. Il repose sur la mesure des déclins de fluorescence de deux molécules modèles, l’anthracène et le paraterphényle, excitées par un flux continu de rayons X, et la séparation des contributions rapide et lente de la lumière émise, aux énergies médicales. Une modélisation analytique des processus physiques conduisant à l’émission de lumière, au regard de la dose déposée, a ensuite été effectuée, faisant apparaître de nombreux résultats originaux. Dans un premier temps, un dispositif expérimental original a été développé, basé sur la technique TCSPC (Time-Correlated Single Photon Counting), afin de pouvoir mesurer des déclins temporels de fluorescence en résolution nanoseconde et sous flux d’irradiation continu. Dans un second temps, nous avons développé une nouvelle approche mathématique permettant d’extraire finement les composantes rapides et lentes du signal. L’analyse des résultats a montré, pour la première fois, l’existence d’un rapport R constant et uniquement fonction du matériau, entre les rendements d’excitation et d’ionisation. Le caractère constant de ce rapport ne peut être attribué qu’à un mécanisme d’autoionisation moléculaire au sein d’un matériau se comportant intrinsèquement comme une chambre d’ionisation proportionnelle pour l’ionisation secondaire de basse énergie. Ceci est en accord total avec la linéarité observée entre l’intensité totale de lumière différée (ionisation) et la dose mesurée par une chambre d’ionisation proportionnelle. Une étude plus approfondie des mécanismes d’excitation, au regard du rapport R, a également permis de montrer, pour la première fois, une proportionnalité directe entre l’intensité totale de la lumière prompte et le dépôt d’une dose que nous avons baptisé dose d’excitation. Cette dose a été observée comme étant de 4 à 14 fois supérieure à celle mesurée par une chambre d’ionisation. Ce résultat original majeur devra impérativement conduire à des études futures afin de mieux comprendre les dégâts infligés à la matière organique et biologique par les excitations. / Organic scintillation is the emission of light by an organic scintillator when irradiated by an external source of radiation depositing enough energy to excite the molecule. Electronic states are populated by the electronic transitions generated by the deposited energy. The states de-excite through radiationless transitions, except for one, the transition between the first electronic state and the ground state where a photon of fluorescence is emitted. This light has two different origins: i) direct excitation caused by primary radiation or secondary electrons which leads to an emission knows as prompt; ii) ionization caused by primary radiation or secondary electrons generate what is known as the delayed component. This fundamental research was based on both theoretical and experimental work. We studied all the different processes in organic scintillation, from the interaction between the incident radiation and matter to the emission of light in order to find the relationship between fluorescence and the deposited dose, to the application to medical dosimetry. Two well known organic scintillators, anthracene and p-terphenyl, were excited using an X-ray source set at typical medical imaging parameters. The light emitted was acquired and an analytical model was used to describe the different processes that led to light emission revealing interesting new results.An experimental setup, based on the Time Correlated Single Photon Counting (TCSPC) technique, was developed to acquire fluorescence decay curves with nanosecond resolution using a continuous X-ray source. Afterwards, these curves were analyzed using an innovative mathematical approach in order to determine the prompt and delayed components.Results showed the ratio, defined as R, between the prompt and delayed components of fluorescence was constant and independent of the energy of the incident X-rays and that the response of the delayed component of fluorescence was linear to an ionization chamber. These observations were explained by considering that the only process taking place within the molecule after excitation was autoionization. Hence, the response of organic scintillator was the same as the one of an ionization chamber. Furthermore, due to the constant ration R, the response of prompt component of fluorescence was linear to the ionization chamber as well. This was the first time this behavior was observed and we referred to it as excitation dose. This dose was between 4 and 14 times bigger than the one measured with the ionization chamber. These original results suggested that energy is deposited mainly through excitation processes, suggesting the need for further studies to better understand the damage caused by excitation to the living.

Ein Ziel der Arbeit war die Entwicklung eines Verfahrens zur 3D-Positionierung auf Basis elektrooptischer Pseudostreckenmessung. Ein zweites Ziel war die Entwicklung eines Reflexgoniometers zur zweiachsigen Winkelmessung. Im Rahmen der Arbeit wurden die Grundlagen zur instrumentellen Umsetzung beider Verfahren erarbeitet, die Genauigkeitspotentiale ermittelt und mögliche Anwendungen für die einzelnen Schlüsseltechnologien und deren Kombination abgeleitet. In einer Prototyp-Entwicklung wurden Vorschläge für die wesentlichen Funktionselemente des räumlichen Weg- bzw. Winkelmesssystems gemacht. Hierzu gehören das kardanisch aufgehängte Etalon, die temperaturstabilisierte Laseroptik und die temperaturkalibrierte CCD der Winkelmesseinheit (Reflexgoniometer), die Systeme zur Erzeugung und Detektion ultrakurzer Laserpulse, eine elastische Optik, Möglichkeiten zur Formung des transversalen Strahlprofils, das TCSPC-System und die zur Auswertung und Kalibrierung notwendigen Algorithmen, wie z.B. die Autokollimation eines Lasers. ("Veröffentlicht von der Deutschen Geodätischen Kommission Reihe C (Dissertationen) unter der Nummer C 614 (München 2008; ISBN 3 7696 5053 0; 2; 144 S.") / One goal of the thesis was the development of a method for three-dimensional positioning based on electro-optical measurement of pseudo ranges. Another goal was the development of a reflex goniometer for biaxial angle measurement. Within the scope of this thesis the basics for the instrumental realisation of both methods were developed, the accuracy potentials were determined and possible applications for the separate key technologies and their combination were deduced. In a prototype development proposals were made for the main functional elements of the spatial distance and angle measurement systems. These include the gimbal mounted etalon, the temperature stabilised laser optics and the temperature calibrated CCD of the angle measurement device (reflex goniometer), the systems for creation and detection of ultrashort laser pulses, an elastic optical device, possibilities of transversal beam shaping, the TCSPC system and the algorithms which are necessary for analysis and calibration, e.g. the autocollimation of a laser.

Ein Ziel der Arbeit war die Entwicklung eines Verfahrens zur 3D-Positionierung auf Basis elektrooptischer Pseudostreckenmessung. Ein zweites Ziel war die Entwicklung eines Reflexgoniometers zur zweiachsigen Winkelmessung. Im Rahmen der Arbeit wurden die Grundlagen zur instrumentellen Umsetzung beider Verfahren erarbeitet, die Genauigkeitspotentiale ermittelt und mögliche Anwendungen für die einzelnen Schlüsseltechnologien und deren Kombination abgeleitet. In einer Prototyp-Entwicklung wurden Vorschläge für die wesentlichen Funktionselemente des räumlichen Weg- bzw. Winkelmesssystems gemacht. Hierzu gehören das kardanisch aufgehängte Etalon, die temperaturstabilisierte Laseroptik und die temperaturkalibrierte CCD der Winkelmesseinheit (Reflexgoniometer), die Systeme zur Erzeugung und Detektion ultrakurzer Laserpulse, eine elastische Optik, Möglichkeiten zur Formung des transversalen Strahlprofils, das TCSPC-System und die zur Auswertung und Kalibrierung notwendigen Algorithmen, wie z.B. die Autokollimation eines Lasers. ("Veröffentlicht von der Deutschen Geodätischen Kommission Reihe C (Dissertationen) unter der Nummer C 614 (München 2008; ISBN 3 7696 5053 0; 2; 144 S.") / One goal of the thesis was the development of a method for three-dimensional positioning based on electro-optical measurement of pseudo ranges. Another goal was the development of a reflex goniometer for biaxial angle measurement. Within the scope of this thesis the basics for the instrumental realisation of both methods were developed, the accuracy potentials were determined and possible applications for the separate key technologies and their combination were deduced. In a prototype development proposals were made for the main functional elements of the spatial distance and angle measurement systems. These include the gimbal mounted etalon, the temperature stabilised laser optics and the temperature calibrated CCD of the angle measurement device (reflex goniometer), the systems for creation and detection of ultrashort laser pulses, an elastic optical device, possibilities of transversal beam shaping, the TCSPC system and the algorithms which are necessary for analysis and calibration, e.g. the autocollimation of a laser.