Advanced Filter Solutions for High-performance Millimetre and Submillimetre-wave Systems

This thesis is devoted to the investigation of advanced filter design solutions for high-performance millimetre and submillimetre-wave systems. Each of the proposed design solutions are enabled using waveguide-based technologies with the aim of advancing future generations of satellite communications, radar, and remote sensing. As trends for frequency allocations move to higher and higher frequency bands, engineers are faced with increasingly complex challenges such as the degradation of component performance, the inability to correctively tune the performance, or scenarios that all together make circuits infeasible. In light of these challenges, this work seeks to advance the current literature on filter design and proposes many unique design solutions for overcoming manufacturing and accuracy limitations, reducing the transmission losses, and reducing the overall design complexity. Each of the proposed filter solutions that are presented in this thesis are based on either a novel structural design or a novel technology. Each of the proposed designs are presented with functional prototypes as a means of verifying the theory. In the majority of cases, prototypes have been manufactured using high-precision computer numerical control (CNC) milling, and in several articles, exploratory activities with the use of alternative technologies such as stereolithography (SLA) 3D-printing and deep-reactive ion etching (DRIE) are presented. Prior to the presentation of the filter designs, an overview on the design and synthesis of millimetre-wave filters and diplexers is provided and serves as a foundation for the coupling matrix descriptions of symmetric and asymmetric resonator designs throughout this work

Submillimeter wave heterodyne receiver

In an embodiment, a submillimeter wave heterodyne receiver includes a finline ortho-mode transducer comprising thin tapered metallic fins deposited on a thin dielectric substrate to separate a vertically polarized electromagnetic mode from a horizontally polarized electromagnetic mode. Other embodiments are described and claimed

Optimization of multicore optical fibers with fiber Bragg gratings towards bend and shape sensing

A shape sensor based on fiber Bragg gratings (FBGs) in multicore fibers is a complex device with multiple factors which have to be accounted for a successful measure- ment system. In this dissertation, I considered several aspects of such shape and curvature sensors

Distributed radiofrequency signal processing based on space-division multiplexing fibers

[EN] Space-division multiplexing fibers emerged as a promising solution to overcome the imminent capacity crunch of conventional singlemode fiber networks. Despite these fibers were initially conceived as distribution media for long-haul high-capacity digital communications, they can be applied to a wide variety of scenarios including centralized radio access networks for wireless communications, data-center interconnects, Microwave Photonics signal processing and fiber sensing. Particular interest is raised by emerging communications paradigms, such as 5G and The Internet of Things, which require a full integration between the optical fiber and the wireless networks segments. Microwave Photonics, discipline that focuses on the generation, processing, control and distribution of radiofrequency signals by photonics means, is called to play a decisive role. One of the major challenges that Microwave Photonics has to overcome to satisfy next-generation communication demands relates to the reduction of size, weight and power consumption while assuring broadband seamless reconfigurability and stability. There is one revolutionary approach that has however been left untapped in finding innovative ways to address that challenge: exploiting space, the last available degree of freedom for optical multiplexing. In this Thesis, we propose to exploit the inherent parallelism of multicore and few-mode fibers to implement sampled discrete true time delay lines, providing, in a single optical fiber, a compact and efficient approach for both Microwave Photonics signal distribution and processing. For the multicore fiber approach, we study the influence of the refractive index profile of each heterogeneous core on the propagation characteristics as to feature specific group delay and chromatic dispersion values. We designed and fabricated two different heterogeneous trench-assisted 7-core fibers that behave as sampled true time delay lines. While one of them was fabricated by using 7 different preforms to feature a plenary performance, the other one employed a single preform with the aim of minimizing fabrication costs. In the case of few-mode fibers, we propose the implementation of a tunable true time delay line by means of a custom-designed fiber with a set of inscribed long period gratings that act as mode converters to properly tailor the sample group delays. We designed and fabricated a true time delay line on a 4-mode fiber by inscribing 3 long period gratings at specific positions along the fiber link. As a proof-of-concept validation, we experimentally demonstrated different Microwave Photonics signal processing functionalities implemented over both multicore and few-mode fiber approaches. This work opens the way towards the development of distributed signal processing for microwave and millimeter wave signals in a single optical fiber. These true time delay lines can be applied to a wide range of Information and Communication Technology paradigms besides fiber-wireless communications such as broadband satellite communications, distributed sensing, medical imaging, optical coherence tomography and quantum communications.[ES] La multiplexación por división espacial en fibras ópticas surgió como una solución prometedora al inminente colapso en la capacidad de las redes de fibra monomodo convencionales. Aunque estas fibras fueron concebidas inicialmente como medio de distribución en comunicaciones digitales de larga distancia y alta capacidad, pueden emplearse en una amplia variedad de escenarios, incluyendo redes de acceso radio centralizadas para comunicaciones inalámbricas, interconexiones en centros de datos, así como procesado de señal en Fotónica de Microondas y sensado en fibra. Los paradigmas de comunicaciones emergentes despiertan un interés particular, como 5G y el Internet de las Cosas, que requieren una integración total entre el segmento de red de fibra óptica y el inalámbrico. La Fotónica de Microondas, disciplina que se focaliza en la generación, procesado, control y distribución de señales de radiofrecuencia por medio de la fotónica, está destinada a jugar un papel decisivo. Uno de los mayores desafíos que la Fotónica de Microondas debe superar para satisfacer los requisitos de las nuevas generaciones de comunicaciones se basa en la reducción de tamaño, peso y consumo de potencia, mientras se garantiza reconfiguración y estabilidad de banda ancha. Encontramos aquí un enfoque revolucionario capaz de abordar este desafío de una manera innovadora que, sin embargo, no ha sido aprovechado en este contexto: la explotación del espacio, el último grado de libertad para multiplexación óptica. En esta Tesis, proponemos explotar el paralelismo inherente de las fibras ópticas multinúcleo y de pocos modos para implementar líneas de retardo en tiempo real muestreadas que proporcionan, en una sola fibra óptica, una solución compacta y eficiente tanto para distribución como para procesado de señales de Fotónica de Microondas. En el caso de fibras multinúcleo, estudiamos la influencia del perfil de índice de refracción de cada núcleo heterogéneo en las características de propagación para que exhiba unos valores concretos de retardo de grupo y dispersión cromática. Diseñamos y fabricamos dos fibras distintas de 7 núcleos con zanjas que se comportan como líneas de retardo en tiempo real muestreadas. Mientras que una de ellas se fabricó utilizando 7 preformas diferentes para garantizar un funcionamiento completo, la segunda se fabricó utilizando una única preforma con el objetivo de minimizar costes de fabricación. En el caso de fibras de pocos modos, proponemos la implementación de líneas de retardo en tiempo real sintonizables mediante el uso de una fibra específicamente diseñada y la inscripción de un conjunto de redes de difracción de periodo largo que actúan como conversores de modos para ajustar adecuadamente el retardo de grupo de las muestras. Diseñamos y fabricamos una línea de retardo en tiempo real en una fibra de 4 modos mediante la inscripción de 3 redes de difracción de periodo largo en posiciones concretas a lo largo de enlace de fibra. Como validación de prueba de concepto, demostramos experimentalmente diferentes funcionalidades de procesado de señal de Fotónica de Microondas implementadas en fibras multinúcleo y de pocos modos. Este trabajo abre el camino hacia el desarrollo del procesado de señal distribuido para señales de microondas y ondas milimétricas en una única fibra óptica. Además, las líneas de retardo en tiempo real desarrolladas pueden aplicarse a una amplia variedad de paradigmas de Tecnologías de la Información y Comunicaciones más allá de las comunicaciones radio sobre fibra, como es el caso de las comunicaciones de banda ancha por satélite, el sensado distribuido, la imagen médica, la tomografía óptica coherente y las comunicaciones cuánticas.[CA] La multiplexació per divisió espacial en fibres òptiques va sorgir com una solució prometedora a l'imminent col·lapse en la capacitat de les xarxes de fibra monomode convencionals. Encara que estes fibres foren concebudes inicialment com a mitjà de distribució en comunicacions digitals de llarga distància i alta capacitat, poden emprar-se en una àmplia varietat d'escenaris, incloent xarxes d'accés radio centralitzades per a comunicacions sense fils, interconnexions en centres de dades, així com processat de senyal en Fotònica de Microones i sensat en fibra. Els paradigmes de comunicacions emergents desperten un interès particular, com el 5G i la Internet de les Coses, que requereixen una integració total entre els segments de xarxa de fibra òptica i el de sense fils. La Fotònica de Microones, disciplina que es focalitza en la generació, processat, control i distribució de senyals de radiofreqüència per mitjà de la fotònica, està destinada a jugar un paper decisiu. Un dels majors desafiaments que la Fotònica de Microones ha de superar per satisfer els requisits de les noves generacions de comunicacions es basa en la reducció de grandària, pes i consum de potència, mentre es garanteix reconfiguració i estabilitat de banda ampla Trobem ací un enfocament revolucionari capaç d'abordar aquest desafiament d'una manera innovadora que, no obstant això, no ha sigut aprofitat encara en este context: la explotació de l'espai, l'últim grau de llibertat per a multiplexat òptic. En aquesta Tesi, proposem explotar el paral·lelisme inherent de les fibres òptiques multinucli i de pocs modes per a implementar línies de retard en temps real de mostres discretes que proporcionen, en una sola fibra òptica, una solució compacta i eficient tant per a distribució com per a processat de senyals de Fotònica de Microones. En el cas de fibres multinucli, estudiem la influència del perfil d'índex de refracció de cada nucli heterogeni en les característiques de propagació perquè exhibisca uns valors concrets de retard de grup i dispersió cromàtica. Dissenyem i fabriquem dues fibres distintes de 7 nuclis amb rases que es comporten com a línies de retard en temps real mostrejades. Mentre que una d'elles es va fabricar utilitzant 7 preformes diferents per a garantir un funcionament complet, la segona va fabricar-se utilitzant una única preforma amb l'objectiu de minimitzar costos de fabricació. En el cas de fibres de pocs modes, proposem la implementació de línies de retard en temps real sintonitzables mitjançant l'ús d'una fibra específicament dissenyada i la inscripció d'un conjunt de xarxes de difracció de període llarg que actuen com a convertidors de modes per tal d'ajustar adequadament el retard de grup de les mostres. Dissenyem i fabriquem una línia de retard en temps real en una fibra de 4 modes mitjançant la inscripció de 3 xarxes de difracció de període llarg en posicions concretes al llarg de l'enllaç de fibra. Com a validació de proba de concepte, demostrem experimentalment diferents funcionalitats de processat de senyal de Fotònica de Microones implementades en fibres multinucli i de pocs modes. Aquest treball obri el camí cap al desenvolupament del processat de senyal distribuït per a senyals de microones i ones mil·limètriques en una única fibra òptica. A més, aquestes línies de retard en temps real poden aplicar-se a una àmplia varietat de paradigmes de Tecnologies de la Informació i Comunicacions més enllà de les comunicacions radio sobre fibra, com es el cas de les comunicacions de banda ampla per satèl·lit, el sensat distribuït, la imatge mèdica, la tomografia òptica coherent i les comunicacions quàntiques.Agradezco al Ministerio de Economía y Competitividad del Gobierno de España por la financiación recibida mediante la ayuda FPI.García Cortijo, S. (2020). Distributed radiofrequency signal processing based on space-division multiplexing fibers [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/147858TESI

Lightwave planar circuits based on organic materials for filtering and sensing

This thesis investigates in detail optical filters based on two phenomena and their applicability in photonics devices. The first phenomenon is called Whispering gallery modes, discovered in 1912 from Lord Rayleigh. The second phenomenon investigated in this thesis is the Braggs’s law, to develop optical filters

Exploiting MS-based techniques to unveil elusive reaction intermediates of bioinorganic relevance

The periodic table for a medicinal chemist or a biochemist is usually restricted to very few elements. More than 95% of the mass of living systems is indeed composed by carbon, hydrogen, nitrogen and oxygen. Besides, elements present only in trace amount can have irreplaceable roles in the chemistry of life. Even more surprisingly, transition metals completely unrelated to living systems have found their way in therapy and, nowadays, antineoplastic drugs containing for example platinum are widespread. However, many techniques routinely exploited for analyzing chemical reactions in solution fail to characterize the properties of metal complexes, in particular in their interaction with biological molecules. The aim of this thesis is to show how electrospray ionization (ESI) mass spectrometry (MS) may excel in capturing elusive species from solution. One can thus shed light on reaction mechanisms of biological relevance and gain insight about coordination sites of biomolecules in binding metals. This work is focusessed on platinum complexes moving from the PtII-containing anticancer drug cisplatin to novel PtIV complexes, which are promising candidates to be at the forefront of future platinum-based therapies. To obtain structural insights about the species of interest, several MS-based techniques have been exploited. IR multiple photon dissociation (IRMPD) spectroscopy was used to obtain the vibrational features of mass selected species. IRMPD spectroscopy combined with calculations at the DFT level, to interpret the experimental vibrational features, allowed us to tackle a variety of issues. Among them, we could unveil the nature of the encounter complex lying on the reaction coordinate of ligand exchange of cisplatin with model biological targets. IRMPD spectroscopy was also employed to characterize the primary intermediates formed by cisplatin reacting with histidine and methionine, major platination targets in proteins. Eventually, IRMPD kinetics on isomer- and conformer-specific vibrational modes were also used to obtain semi-quantitative information about the conformational landscape of cisplatin derived complexes. Collision induced dissociation (CID) was instead the MS/MS technique of choice to gain information about the gas-phase reactivity of platinum(IV) complexes. Using high-resolution mass spectrometry a complete fragmentation pattern was achieved by assigning an unambiguous molecular formula and so characterizing exotic species generated by reduction of PtIV

Polymer-based 3-D printed 140 to 220 GHz metal waveguide thru lines, twist and filters

This paper demonstrates the current state-of-the-art in low-cost, low loss ruggedized polymer-based 3-D printed G-band (140 to 220 GHz) metal-pipe rectangular waveguide (MPRWG) components. From a unique and exhaustive up-to-date literature review, the main limitations for G-band split-block MPRWGs are identified as electromagnetic (EM) radiation leakage, assembly part alignment and manufacturing accuracy. To mitigate against leakage and misalignment, we investigate a ‘trough-and-lid’ split-block solution. This approach is successfully employed in proof-of-concept thru lines, and in the first polymer-based 3-D printed 90° twist and symmetrical diaphragm inductive iris-coupled bandpass filters (BPFs) operating above 110 GHz. An inexpensive desktop masked stereolithography apparatus 3-D printer and a commercial copper electroplating service are used. Surface roughness losses are calculated and applied to EM (re-)simulations, using two modifications of the Hemispherical model. The 7.4 mm thru line exhibits a measured average dissipative attenuation of only 12.7 dB/m, with rectangular-to-trapezoidal cross-sectional distortion being the main contributor to loss. The 90° twist exhibits commensurate measured performance to its commercial counterpart, despite the much lower manufacturing costs. A detailed time-domain reflectometry analysis of flange quality for the thru lines and 90° twists has also been included. Finally, a new systematic iris corner rounding compensation technique, to correct passband frequency down-shifting is applied to two BPFs. Here, the 175 GHz exemplar exhibits only 0.5% center frequency up-shifting. The trough-and-lid assembly is now a viable solution for new upper-mm-wave MPRWG components. With this technology becoming less expensive and more accurate, higher frequencies and/or more demanding specifications can be implemented