Millimetre-wave radio-over-fibre supported multi-antenna and multi-user transmission

In this thesis, various features of the RoF supported mmW communication for future wireless systems have been analysed including photonic generation of mmW for MIMO operation, performance analysis of mmW MIMO to achieve spatial diversity and spatial multiplexing with analog RoF fronthaul, and multi-user transmission in the 60 GHz-band using multiplexing-over-fibre transport and frequency-selective antenna. A low cost mmW generation system for two independent MIMO signals has been presented, consisting of a single optical Phase Modulator (PM). The different aspects of experimental analysis on RoF-supported mmW MIMO in this thesis, which were not considered before, include use of specific MIMO algorithm to understand the amount of improvement in coverage and data rate for a particular MIMO technique, performance comparison with SISO at several user locations, and verification of optimum RAU physical spacing for a particular transmission distance with the theoretical results. The results show that flexible and wider RAU spacings, required to obtain optimum performance in a mmW MIMO system, can be achieved using the proposed analog RoF fronthaul. The investigation was extended to verification of a method to individual measurement of mmW channel coefficients and performing MIMO processing, which shows that mmW channels are relatively static and analysis can be extended to much longer distances and making projections for N×N MIMO. For mmW multi-user transmission, a novel low cost, low complexity system using single RoF link and single RF chain with single transmitting antenna has been presented and characterized, which was based on large number of RF chains and multiple antenna units previously. The setup involves generation and RoF transport of a composite SCM signal, upconversion at the RAU and transmission of different frequency channels towards spatially distributed users using a frequency-selective Leaky-Wave-Antenna (LWA), to convert Frequency Division Multiplexing (FDM) in to Spatial Division Multiple Access (SDMA). Analysis on low user-signal spacing for the SCM shows the feasibility to serve a large number of users within a specific transmission bandwidth and experimental demonstration to achieve sum rate of 10Gb/s is shown by serving 20 users simultaneously. Furthermore, investigation on SNR degradation of high bandwidth signals due to beamsteering effect of the LWA and theoretical calculations of the sum data rate for different number of users is performed, which shows that the proposed system can provide much higher sum rates with high available SNR. It was also experimentally demonstrated that improvement in coverage and spectral efficiency is obtained by operating multiple LWAs using single RF chain. Finally, an experimental demonstration of a DWDM-RoF based 60 GHz multi-user transmission using single LWA is presented to show the feasibility to extend the setup for a multiple RAU based system, serving each at distinct optical wavelength and performing direct photonic upconversion at the RAU for low cost mmW generation

Optimized, versatile diamond-based sensors : materials, fabrication and novel applications

Quantum sensing as one of the backbones of the second quantum revolution is about to enable a variety of novel applications requiring good spatial resolution and sensitivity. The atomic-sized, negatively charged nitrogen vacancy (NV) color center in single crystal diamond was found to enable magnetic field sensing at the nanoscale. Magnetic sensing using NV centers is enabled by bright photostable emission and optically addressable spin states. Due to its extraordinary coherence time, sensitivities of few nT\Hz^(1/2) can be achieved under ambient conditions. To enhance the spatial resolution of NV-based sensing, it is necessary to approach the NV center to a sample to investigate. Here, a challenging nanofabrication procedure is needed to sculpt the diamond into a photonic nanostructure usable as a scanning probe tip. In this thesis, we report on the progress towards optimizing the applicability of NV centers as quantum sensors. We investigate novel material systems promising for upscaling nanofabrication. By introducing a novel approach to enhance the adhesion of etch masks and novel plasma treatments, we optimize the reliability of the nanofabrication procedure. In addition, we study a novel near-field interaction-based sensing resource. By investigating the interaction of shallow NV centers with a monolayer of WSe2, we were able to show simultaneous near-field and magnetic field sensing using the NV center.Als eine der Säulen der zweiten Quanten-Revolution ermöglicht die Quantensensorik viele neue Anwendungen, die eine gute Ortsau ösung und Sensitivität benötigen. Das atomar kleine, negativ geladene Stickstoff-Fehlstellen (NV) Farbzentrum in einkristallinem Diamant ermöglicht das Detektieren von Magnetfeldern auf Nanomaÿstäben. Magnetfelddetektion mittels NV Zentren wird durch helle, photostabile Emission und optisch adressierbare Spin-Zustände ermöglicht. Aufgrund seiner auÿergewöhnlichen Kohärenzzeit erreicht es Sensitivitäten von einigen nT/Hz^(1/2) unter Umgebungsbedingungen. Zur Verbesserung der Ortsauflösung NV-basierter Sensorik, muss das NV-Zentrum an die zu untersuchende Probe angenähert werden. Dies erfordert einen herausfordernden Nanfabrikationsprozess, um den Diamanten in eine photonische Struktur zu formen, die als Rastersonde nutzbar ist. Diese Arbeit beschreibt Fortschritte zur Optimierung der Anwendbarkeit von NV-Zentren als Quantensensoren. Wir untersuchen neuartige Materialien, die vielversprechend für die Skalierbarkeit des Prozesses sind. Durch neue Ansätze zur Verbesserung der Adhäsion von Ätzmasken und neue Plasmabehandlungen optimieren wir die Zuverlässigkeit der Nanofabrikation. Zudem analysieren wir einen neuen, auf Nahfeldwechselwirkung beruhenden Sensorikansatz. Bei der Untersuchung der Wechselwirkung von oberflächennahen NV-Zentren mit monolagigem WSe2 konnten wir das gleichzeitige Erfassen von Nah- und magnetischen Feldern mittels NV-Zentren zeigen

Multimode fibre broadband access and self-referencing sensor networks

Future Internet Access technologies are supposed to bring us a very performing connection to the main door of our homes. At the same time, new services and devices and their increase use will require data transfers at speeds exceeding 1Gbps inside the building or home at the horizon 2012. Both drivers lead to the deployment of a high-quality, futureproof network inside buildings and homes. This environment may end up taking advantage of optical cabling solutions as an alternative to more traditional copper or pure wireless approaches. Related to this latter fact, the objectives of this work are: • The achievement of a full convergence scenario between optical networks from the telecommunication services providers to the end users underscores the necessity of accurate and realistic fibre models in assessing the performance of broadband access networks with the premises of high-capacity and total compatibility. Silicabased MMFs and PF GIPOFs are the most promising candidates for such a convergence within the in-building/home scenario. Contributions to a better understanding of the possibilities of signal transmission outside the baseband of such fibres are investigated, in order to extend their capabilities, together with the evaluation of current fibre frequency response theoretical models by means of an extensive set of measurements. • The achievement of a full convergence scenario between optical networks from the telecommunication services providers to the end users is also contingent on research and development in the field of optical fibre sensors, mainly driven by the growing demand of fully building/home and industry automation, leading to a reliable integration of the optical networks. Related to this, development of multiplexing and measurement techniques for fibre-optic intensity-based sensors are analyzed and experimentally investigated. In the sensor network topology proposed, by replacing the fibre delay line with an electronic delay in the reception stage, it is possible to avoid long fibre delay coils in the remote sensing points and achieving a compact, flexible and re-configurable self-referencing technique. Applications in both scenarios can be considered, on the one hand the in-building/home network and on the other hand the WDM-PON access network topology through which operators provision the different services. -----------------------------------------------------------------------------------------------------------------------------------------------------------------------------La demanda e incursión en la sociedad de nuevos servicios multimedia, tales como televisión por Internet (IPTV, Internet Protocol Television) o video-bajo-demanda (VoD, Video on Demand) junto con el incremento del tráfico de datos requerido para nuevas aplicaciones como la televisión por alta definición (HDTV, High-Definition Television) y transferencias P2P (Peer-to-Peer) exigen un aumento de la capacidad de las redes de datos desplegadas hoy en día. Para hacer frente a este aumento de la demanda de capacidad de las redes de acceso, los proveedores de estos servicios multimedia están reemplazando las infraestructuras de las redes de acceso basadas en cable coaxial, tales como xDSL (x- Digital Subscriber Line), por otras nuevas de mayor capacidad desplegadas en fibra óptica, permitiendo la interconexión de los nodos de red con los múltiples hogares y negocios de los abonados, constituyendo el núcleo de lo que es conocido como “fibra hasta el hogar/nodo/edificio” o redes FTTx. Tradicionalmente el despliegue de las redes ópticas se ha realizado mediante fibra óptica monomodo de sílice (SMF, Singlemode Fibre). Ello es debido a su gran ancho de banda que permite una gran capacidad de transporte de servicios y datos. Es por ello que en base a este tipo de fibra se ha realizado el despliegue de redes de distribución y metropolitanas y, de un tiempo a esta parte, incluso penetrando su instalación en las redes de acceso. Junto con lo anteriormente expuesto, existe una necesidad de convergencia de servicios e infraestructuras dentro de las redes de acceso. Actualmente, cables coaxiales, par trenzado de cobre e incluso señales inalámbricas se encuentran entremezcladas dentro del hogar proporcionando servicios diferentes con apenas cooperación entre ellos. Una infraestructura común dentro del hogar en el que una gran cantidad de servicios pudieran ser integrados y soportados por la misma sería un aspecto deseable. Y es más, frente a las desventajas de infraestructuras basadas en cable de cobre (cable coaxial y par trenzado) como son susceptibilidad a interferencias electromagnéticas, presencia de crosstalk y relativa baja capacidad de transporte de datos, las fibras ópticas (tanto en su versión monomodo como multimodo) presentan las ventajas de un menor volumen, mayor flexibilidad y menor peso junto con una capacidad mayor de transmisión de datos sobre distancias mayores. Es por esto que éstas últimas constituyen la base para las futuras redes de acceso en el hogar

Orthogonal frequency division multiplexing for next generation optical networks

Next generation optical networks will be required to provide increased data throughput on a greater number of optical channels and will also have to facilitate network flexibility in order to adapt to dynamic traffic patterns. Furthermore, the potentially wide deployment of optical Access and Metropolitan networks in particular require that these challenges are met in a cost effect manner. This thesis examines the use of Orthogonal Frequency Division Multiplexing (OFDM) as a means of helping to meet these requirements for next generation optical systems with a high market volume. OFDM is a multi–carrier modulation technique which exhibits high spectral efficiency and a tolerance to chromatic dispersion making it an excellent candidate for use in next generation optical networks. The work presented in this thesis shows how the use of OFDM in conjunction with novel laser devices and direct detection can be used to construct cost effective, low footprint optical systems. These systems are capable of providing >10Gb/s per optical channel and are suitable for implementation as optical access networks. Furthermore, OFDM is shown to be a realistic candidate for use in an optical switching environment where external modulation is employed and, as such, can be considered for use in next generation metropolitan networks

Understanding Quantum Technologies 2022

Understanding Quantum Technologies 2022 is a creative-commons ebook that provides a unique 360 degrees overview of quantum technologies from science and technology to geopolitical and societal issues. It covers quantum physics history, quantum physics 101, gate-based quantum computing, quantum computing engineering (including quantum error corrections and quantum computing energetics), quantum computing hardware (all qubit types, including quantum annealing and quantum simulation paradigms, history, science, research, implementation and vendors), quantum enabling technologies (cryogenics, control electronics, photonics, components fabs, raw materials), quantum computing algorithms, software development tools and use cases, unconventional computing (potential alternatives to quantum and classical computing), quantum telecommunications and cryptography, quantum sensing, quantum technologies around the world, quantum technologies societal impact and even quantum fake sciences. The main audience are computer science engineers, developers and IT specialists as well as quantum scientists and students who want to acquire a global view of how quantum technologies work, and particularly quantum computing. This version is an extensive update to the 2021 edition published in October 2021.Comment: 1132 pages, 920 figures, Letter forma

Realization Limits of Impulse-Radio UWB Indoor Localization Systems

In this work, the realization limits of an impulse-based Ultra-Wideband (UWB) localization system for indoor applications have been thoroughly investigated and verified by measurements. The analysis spans from the position calculation algorithms, through hardware realization and modeling, up to the localization experiments conducted in realistic scenarios. The main focus was put on identification and characterization of limiting factors as well as developing methods to overcome them

DETERMINING THE QUALITY OF PASTEURISED AND HOMOGENISED COW MILK USING MICROWAVE SENSORS

More than 6 billion people worldwide consume milk and milk products and this number is rapidly growing every year (FAO, 2015a), there are numerous occurrences where the milk quality was below acceptable standards causing severe health hazards among consumers including young children. The aim of this research work is to design and develop a novel, microwave spectroscopy, approach for determination of overall quality of milk. In particular, this quality determination of milk products was achieved by identification of deterioration or spoilage of milk over time, classification of the milk product based on composition (e.g. fat content), in addition to the contamination (e.g. adulteration due to presence of detergents, urea). An extensive literature review was carried out to establish the scope of the PhD work and in order to achieve the objectives. Current advancements were studied along with the traditional methods of milk quality testing to identify the key areas where further development can take place to enable the quality control of milk products outside the laboratory premises. This work addresses the drawbacks in currently employed methodologies and attempts to overcome or minimize their overall limiting effect. The application of this sensor system is aimed within the milk supply-chain hierarchy after the production at dairy plants and before sale to allow easy and real-time quality testing. The dielectric property tests were conducted to produce unique spectral signatures for three mainly consumed categories of fresh milk; whole milk, semi-skimmed milk and skimmed milk bought from a supermarket over a period of a week, which served to build a reference database. Based on these spectral signatures for the three categories of milk, a planar, microwave resonator sensor acting as a fluidic sensor was designed, simulated and fabricated to determine spoilage, classification of milk and identify presence of contamination. This work has achieved distinct results to verify the statement, followed by validation, to serve as a platform for the establishment of a laboratory based prototype model to test overall quality of Milk products, with coefficient of determination R2 ≥ 0.95 in all experimental measurements

NIAC Phase II Orbiting Rainbows: Future Space Imaging with Granular Systems

Inspired by the light scattering and focusing properties of distributed optical assemblies in Nature, such as rainbows and aerosols, and by recent laboratory successes in optical trapping and manipulation, we propose a unique combination of space optics and autonomous robotic system technology, to enable a new vision of space system architecture with applications to ultra-lightweight space optics and, ultimately, in-situ space system fabrication. Typically, the cost of an optical system is driven by the size and mass of the primary aperture. The ideal system is a cloud of spatially disordered dust-like objects that can be optically manipulated: it is highly reconfigurable, fault-tolerant, and allows very large aperture sizes at low cost. This new concept is based on recent understandings in the physics of optical manipulation of small particles in the laboratory and the engineering of distributed ensembles of spacecraft swarms to shape an orbiting cloud of micron-sized objects. In the same way that optical tweezers have revolutionized micro- and nano-manipulation of objects, our breakthrough concept will enable new large scale NASA mission applications and develop new technology in the areas of Astrophysical Imaging Systems and Remote Sensing because the cloud can operate as an adaptive optical imaging sensor. While achieving the feasibility of constructing one single aperture out of the cloud is the main topic of this work, it is clear that multiple orbiting aerosol lenses could also combine their power to synthesize a much larger aperture in space to enable challenging goals such as exo-planet detection. Furthermore, this effort could establish feasibility of key issues related to material properties, remote manipulation, and autonomy characteristics of cloud in orbit. There are several types of endeavors (science missions) that could be enabled by this type of approach, i.e. it can enable new astrophysical imaging systems, exo-planet search, large apertures allow for unprecedented high resolution to discern continents and important features of other planets, hyperspectral imaging, adaptive systems, spectroscopy imaging through limb, and stable optical systems from Lagrange-points. Furthermore, future micro-miniaturization might hold promise of a further extension of our dust aperture concept to other more exciting smart dust concepts with other associated capabilities. Our objective in Phase II was to experimentally and numerically investigate how to optically manipulate and maintain the shape of an orbiting cloud of dust-like matter so that it can function as an adaptable ultra-lightweight surface. Our solution is based on the aperture being an engineered granular medium, instead of a conventional monolithic aperture. This allows building of apertures at a reduced cost, enables extremely fault-tolerant apertures that cannot otherwise be made, and directly enables classes of missions for exoplanet detection based on Fourier spectroscopy with tight angular resolution and innovative radar systems for remote sensing. In this task, we have examined the advanced feasibility of a crosscutting concept that contributes new technological approaches for space imaging systems, autonomous systems, and space applications of optical manipulation. The proposed investigation has matured the concept that we started in Phase I to TRL 3, identifying technology gaps and candidate system architectures for the space-borne cloud as an aperture

Toward an active CMOS electronics-photonics platform based on subwavelength structured devices

The scaling trend of microelectronics over the past 50 years, quantified by Moore’s Law, has faced insurmountable bottlenecks, necessitating the use of optical communication with its high bandwidth and energy efficiency to further improve computing performance. Silicon photonics, compatible with CMOS platform manufacturing, presents a promising means to achieve on-chip optical links, employing highly sensitive microring resonator devices that demand electronic feedback and control due to fabrication variations. Achieving the full potential of both technologies requires tight integration to realize the ultimate benefits of both realms of technology, leading to the convergence of microelectronics and photonics. A promising approach for achieving this convergence is the monolithic integration of electronics and photonics on CMOS platforms. A critical milestone was reached in 2015 with the demonstration of the first microprocessor featuring photonic I/O (Chen et al, Nature 2015), accomplished by integrating transistors and photonic devices on a single chip using a monolithic CMOS silicon-on-insulator (SOI) platform (GlobalFoundries 45RFSOI, 45 nm SOI process) without process modifications, thus known as the "zero-change" approach. This dissertation focuses on leveraging the fabrication capabilities of advanced monolithic electronic-photonic 45 nm CMOS platforms, specifically high-resolution lithography and small feature size doping implants, to realize photonic devices with subwavelength features that could potentially provide the next leap in integrated optical links performance, beyond microring resonator based links. Photonic crystal (PhC) nanobeam cavities can support high-quality resonance modes while confining light in a small volume, enhancing light-matter interactions and potentially enabling ultimate efficiencies in active devices such as modulators and photodetectors. However, PhC cavities have been overshadowed by microring resonators due to two challenges. First, their fabrication demands high lithography resolution, which excludes most standard SOI photonic platforms as viable options for creating these devices. Secondly, the standing-wave nature of PhC nanobeam cavities complicates their integration into wavelength-division multiplexing (WDM) optical links, causing unwanted reflections when coupled evanescently to a bus waveguide. In this work, we present PhC nanobeam cavities with the smallest footprint, largest intrinsic quality factor, and smallest mode volume to be demonstrated to date in a monolithic CMOS platform. The devices were fabricated in a 45 nm monolithic electronics–photonics CMOS platform optimized for silicon photonics, GlobalFoundries 45CLO, exhibiting a quality factor in excess of 100,000 the highest among fully cladded PhC nanobeam cavities in any SOI platform. Furthermore to eliminate reflections, we demonstrate an approach using pairs of PhC nanobeam cavities with opposite spatial mode symmetries to mimic traveling-wave-like ring behavior, enabling efficient and seamless WDM link integration. This concept was extended to realize a reflectionless microring resonator unit with two microrings operating as standing-wave cavities. Using this scheme with standing-wave microring resonators could lead to an optimum geometry for microring modulators with interdigitated p-n junctions in terms of modulation efficiency in a manner that allows for straightforward WDM cascading. This work also presents the first demonstration of resonant-structure-based modulators in the GlobalFoundries 45CLO platform. We report the first-ever demonstration of a PhC modulator in a CMOS platform, featuring a novel design with sub-wavelength contacts on one side allowing it to benefit from the "reflection-less"' architecture. Additionally, we also report the first demonstration of microring modulators. The most efficient devices exhibited electro-optical bandwidths up to 30 GHz, and 25 Gbps non-return-to-zero (NRZ) on-off-keyed (OOK) modulation with 1 dB insertion loss and 3.1 dB extinction ratio. Finally, as the complexity of silicon photonic systems-on-a-chip (SoC) increases to enable new applications such as low-energy data links, quantum optics, and neuromorphic computing, the need for in-situ characterization of individual components becomes increasingly important. By combining Near-field scanning optical microscopy (NSOM) with a flip-chip post-processing technique, this dissertation demonstrates a method to non-invasively perform NSOM scans of a photonic device within a large-scale CMOS-photonic circuit, without interfering with the performance and packaging of the photonics and electronics, making it a valuable tool for future development of high performance photonic circuits and systems