This thesis describes an optical fibre network that uses a bus topology and Code Division Multiple Access (CDMA). Various potential configurations are analysed and compared and it is shown that a serious limitation of optical CDMA schemes using incoherent correlators is the effect of optical beating due to the presence of multiple incoherent optical signals at the receiver photodiode. The network proposed and analysed in this thesis avoids beating between multiple optical fields because it only uses a single, shared, optical source. It does this through the SLIM (Single Light-source with In-line Modulation) configuration in which there is a continuously-operating light source at the head-end of a folded bus, and modulators at the nodes to impose signals on the optical field in the form of pulses of darkness which propagate along the otherwise continuously bright bus. Optical CDMA can use optical-fibre delay-line correlators as matched filters, and these may be operated either coherently or incoherently.Coherent operation is significantly more complex than incoherent operation, but incoherent correlators introduce further beating even in a SLIM network. A new design of optical delay-line correlator, the hybrid correlator, is therefore proposed, analysed and demonstrated. It is shown to eliminate beating. A model of a complete network predicts that a SLIMbus using optical CDMA with hybrid correlators can be operated at TeraBaud rates with the number of simultaneous users limited by multiple access interference (MAI), determined only by the combinatorics of the code set.

This dissertation addresses three research challenges in planar lightwave circuit (PLC) optical signal processing. 1. Dynamic localization, a relatively new class of quantum phenomena, has not been demonstrated in any system to date. To address this challenge, the quantum system was mapped to the optical domain using a set of curved, coupled PLC waveguides in aluminum gallium arsenide (AlGaAs). The devices demonstrated, for the first time, exact dynamic localization in any system. These experiments motivate further mappings of quantum phenomena in the optical domain, leading toward the design of novel optical signal processing devices using these quantum-analog effects. 2. The PLC microresonator promises to reduce PLC device size and increase optical signal processing functionality. Microresonators in a parallel cascaded configuration, called "side coupled integrated spaced sequence of resonators" (SCISSORs), could offer very interesting dispersion compensation abilities, if a sufficient number of rings is present to produce fully formed "Bragg" gaps. To date, a SCISSOR with only three rings has been reported in a high-index material system. In this work, one, two, four and eight-ring SCISSORs were fabricated in AlGaAs. The eight-ring SCISSOR succeeded in producing fully formed Bragg peaks, and offers a platform to study interesting linear and nonlinear phenomena such as dispersion compensators and gap solitons. 3. PLCs are ideal candidates to satisfy the projected performance requirements of future microchip interconnects. In addition to data routing, these PLCs must provide over 100-bit switchable delays operating at ~ 1 Tbit/s. To date, no low loss optical device has met these requirements. To address this challenge, an ultrafast, low loss, switchable optically controllable delay line was fabricated in AlGaAs, capable of delaying 126 bits, with a bit-period of 1.5 ps. This successful demonstrator offers a practical solution for the incorporation of optics with microelectronics systems. The three aforementioned projects all employ, in their unique way, the coupling of light between PLC waveguides in AlGaAs. This central theme is explored in this dissertation in both its two- and multi-waveguide embodiments.

This dissertation addresses three research challenges in planar lightwave circuit (PLC) optical signal processing. 1. Dynamic localization, a relatively new class of quantum phenomena, has not been demonstrated in any system to date. To address this challenge, the quantum system was mapped to the optical domain using a set of curved, coupled PLC waveguides in aluminum gallium arsenide (AlGaAs). The devices demonstrated, for the first time, exact dynamic localization in any system. These experiments motivate further mappings of quantum phenomena in the optical domain, leading toward the design of novel optical signal processing devices using these quantum-analog effects. 2. The PLC microresonator promises to reduce PLC device size and increase optical signal processing functionality. Microresonators in a parallel cascaded configuration, called "side coupled integrated spaced sequence of resonators" (SCISSORs), could offer very interesting dispersion compensation abilities, if a sufficient number of rings is present to produce fully formed "Bragg" gaps. To date, a SCISSOR with only three rings has been reported in a high-index material system. In this work, one, two, four and eight-ring SCISSORs were fabricated in AlGaAs. The eight-ring SCISSOR succeeded in producing fully formed Bragg peaks, and offers a platform to study interesting linear and nonlinear phenomena such as dispersion compensators and gap solitons. 3. PLCs are ideal candidates to satisfy the projected performance requirements of future microchip interconnects. In addition to data routing, these PLCs must provide over 100-bit switchable delays operating at ~ 1 Tbit/s. To date, no low loss optical device has met these requirements. To address this challenge, an ultrafast, low loss, switchable optically controllable delay line was fabricated in AlGaAs, capable of delaying 126 bits, with a bit-period of 1.5 ps. This successful demonstrator offers a practical solution for the incorporation of optics with microelectronics systems. The three aforementioned projects all employ, in their unique way, the coupling of light between PLC waveguides in AlGaAs. This central theme is explored in this dissertation in both its two- and multi-waveguide embodiments.

Theory, design, fabrication and characterization of on-chip optical beam steering systems are presented in this dissertation. Silicon photonics is being considered for integration with conventional CMOS technology for large-band width and low loss on and off-chip communications. We choose silicon nanomembrane, or silicon-on-insulator (SOI) substrates for implementation of large-angle and agile beam steeres. While working on the targeted device, we contributed to the theory, modeling, engineering and implementation of different building blocks. Multimode-interference couplers (MMIs) constitute important parts of this dissertation. These devices are commonly used as on-chip beam splitters, optical switches and on-chip static phase shifters. The MMIs’ principles of operation are suited in more details and design rules are derived for the first time. MMI based beam splitters with number of outputs as large as 12 are fabricated and tested on SOI wafers. Traditionally, MMIs devices were designed by means of computationally expensive numerical simulations. Numerically and experimentally, we show that our analytical design rules make design of MMIs with low insertion loss and highly uniform outputs possible without additional optimization processes. Optical phased arrays include phase shifter blocks. In the first prototype, we use micro-heaters for tuning the optical phase. The bread-loafing effect, which is generally considered an undeniable phenomenon in the silicon industry, is engineered to realize a mechanical structure to efficiently direct heat toward the silicon waveguides. We also investigate slow light photonic crystal based delay lines to be used as phase shifters. An important drawback of such devices is the low coupling efficiency between slow-light photonic crystal waveguides and fast light strip waveguides. We numerically and experimentally investigate the coupling efficiency, and show for the first time that a few-period long fast-light photonic crystal waveguide without any group index tapering suffices for efficient coupling. The prototype is fabricated, packaged and tested and optical beam steering angle over ±30degrees is demonstrated. Finally, preliminary investigations for 3D implementation of the beam steerer system are presented to clarify the approaches to take for future works. / text

Silicon photonics has been a rapidly growing subfield of integrated optics and optoelectronic in the last decade and is currently considered a mature technology. The main thrust behind the growth is its compatibility with the mature and low-cost microelectronic integrated circuits fabrication process. In recent years, several active and passive photonic devices and circuits have been demonstrated on silicon. Optical delay lines are among important silicon photonic devices, which are essential for a variety of photonic system applications including optical beam-forming for controlling phased-array antennas, optical communication and networking systems and optical coherence tomography. In this thesis, several types of delay lines based on apodized grating waveguides are proposed and demonstrated. Simulation and experimental results suggest that these novel devices can provide high optical delay and tunability at very high bit rate. While most of silicon photonics research has focused in the near-infrared wavelengths, extending the operating wavelength range of the technology into in the 3–5 µm, or the mid-wave infrared regime, is a more recent field of research. A key challenge has been that the standard silicon-on-insulator waveguides are not suitable for the midinfrared, since the material loss of the buried oxide layer becomes substantially high. Here, the silicon-on-sapphire waveguide technology, which can extend silicon’s operating wavelength range up to 4.4 µm, is investigated. Furthermore, silicon-on-nitride waveguides, boasting a wide transparent range of 1.2–6.7 μm, are demonstrated and iv characterized for the first time at both mid-infrared (3.39 μm) and near-infrared (1.55 μm) wavelengths.

Microwave Photonics(MWP) has been defined as the study of photonic devices which operate at microwave frequencies and also their applications to microwave and optical systems. One or more electrical signals at microwave frequencies are transported over the optic link ,with electrical to optical and optical to electrical conversion on the transmission and receiving side respectively. The key advantages of microwave photonic links over conventional electrical transmission systems such as coaxial cables or waveguides ,includes reduced size, weight and cost, immunity to electromagnetic interference ,low dispersion and high data transfer capacity. Integrated Optics is the name given to a new generation of opto-electronic systems in which the familiar wires and cables are replaced by light-waveguiding optical fibers, and conventional integrated circuits are replaced by optical integrated circuits (OICs).Microwave Photonics with photonic integration can add the benefits of reduction in system size, losses, short path lengths leading to more efficient cost effective systems. In this thesis, a new approach for using 1-D linear arrays of curved waveguides as delay lines is presented. We propose a design for a passive phase shifter obtained by curved waveguide delay lines. The modulated RF signal obtains the phase shift in the optical domain which is transferred to the RF signal by heterodyning techniques .This phase shift is independent of the RF frequency and hence the Beam squinting which occurs in the conventional RF phase shifter systems is avoided in the proposed system. Switching between different lengths of the bent/curved waveguides can produce variable phase shifts ranging from 0 to 2 radians. The use of curved waveguides for delay generation and optimization of various parameters are the main topics of the research problem. The need for delay line is large and most of these were implemented previously using long optical fiber cables. More precise delays could be obtained by using waveguide delay lines as compared to fiber delay lines. Waveguides paves way for design in smaller dimensions ranging from m to nm in integrated optics. The differential phase shift for a signal propagating in a waveguide from waveguide theory is given as which clearly indicates that the differential phase shifts could be obtained in accordance with differential path lengths Δl with β as the propagation constant. S-bend waveguide sections of different lengths along with straight waveguide as reference for each section are employed. The phase delay is passively obtained by a differential path length change, where various phase shift values can be obtained by switching between different differential path lengths. Since the optical phase delay generated is in- dependent of the input RF frequency. A shift in the RF frequency, at the input will not change the phase or beam pointing angle when the phase shifter is employed for beam pointing in case of Phased Array Antenna applications. A 1-bit phase shifter is the firrst step in the design which could be further extended to n-bit phase shifter. Here 1-bit or n-bit ,is one where n can take any integer value. Each bit is composed of a reference phase signal pathway and a delayed phase signal pathway. When the optical signal goes every single bit through the reference phase the phase shift is ‘0’ radians ,the other is through the delayed path which is . For every n-bit, 2n delays can be obtained. For the 1-bit,2 delays are obtained. Switching between the path lengths is done using the directional coupler switches. Th optimization of different parameters of the S-bend waveguide delay line has been realized and studied. The design and optimisation of a 1-bit optical RF phase shifter is discussed which could be extended to n-bit phase shifters. These S-bends are studied analytically. Beam Propagation Method (BPM)is employed for modeling and simulation of the proposed device. An interferometric configuration is considered for practical measurement of optical phase. In this configuration the phase change is translated into amplitude or intensity measurement. One of the arms of the Maczehdner Interferometer has no path length change while the other arm has an S-bend structure which provides the path length difference as compared to the reference path, and hence produces the necessary phase shift at the output of the interferometer as required. By changing the path length difference between the two arms of the interferometer ,a change in intensity is produced at the output of the interferometer. In this study, integrated optic curved waveguide delay line phase shifters are designed and analyzed, considering the Titanium Di used Lithium Niobate Technology. This is because it has good electro-optic properties necessary for designing switches used for switching between delay segments. Practical parameters that can be fabricated are employed in the design and simulation studies reported here. Fabrication is also done using the Lithium Niobate Technology. However the fabrication studies are excluded from the main stream, as further fabrication studies are necessary to realise the actual devices de- signed. The fabrication aspects are left as scope for further development. The fabricated devices are shown as appendix to the thesis. Organisation of the thesis Chapter 1 gives the introduction to the fields of Microwave Photonics and Integrated optics and its applications. Chapter 2discusses the curved waveguide theory and design with coverage of materials and methods employed in the proposed system. Chapter 3 discusses the different types of delay lines and the design of the 1-bit phase shifter which can be extended to the design of a n-bit phase shifter with both analytical and simulation results. Chapter 4 discusses the method of phase measurement for the n-bit phase shifter and the possible applications where the phase shifter could be employed. Chapter 5 discusses conclusions and future work in the proposed area of work. Appendix A discusses the loss calculations for the Cosine S-bend waveguide. Appendix B gives the fabrication details. The references form the end part of the thesis.

In den letzten Jahrzehnten ist das globale Kommunikationssystem in einem immer größerem Maße ein integraler Bestandteil des täglichen Lebens geworden. Optische Kommunikationssysteme sind die technologische Basis für diese Entwicklung. Nur Fasern können die riesige benötigte Bandbreite bereitstellen. Während für die ersten optischen Übertragungssysteme die Faser als "flacher" Kanal betrachtet werden konnte, machen Wellenlängenmultiplex und steigende Übertragungsraten die Einbeziehung von immer mehr physikalischen Effekten notwendig. Bei einer Erhöhung der Kanaldatenrate auf 40 Gbit/s und mehr ist die statische Kompensation von chromatischer Dispersion nicht mehr ausreichend. Die intrinsische Toleranz der Modulationsformate gegenüber Dispersion nimmt quadratisch mit der Symbolrate ab. Daher können beispielsweise durch Umwelteinflüsse hervorgerufene Dispersionsschwankungen die Dispersionstoleranz der Modulationsformate überschreiten. Dies macht eine adaptive Dispersionskompensation notwendig, was gleichzeitig auch Dispersionsmonitoring erfordert, um den adaptiven Kompensator steuern zu können. Vorhandene Links können mit Restdispersionskompensatoren ausgestattet werden, um sie für Hochgeschwindigkeitsübertragungen zu ertüchtigen. Optische Kompensationstechniken sind unabhängig von der Kanaldatenrate. Daher wird eine Erhöhung der Datenrate problemlos unterstützt. Optische Kompensatoren können WDM-fähig gebaut werden, um mehrere Kanäle auf einmal zu entzerren. Das Buch beschäftigt sich mit optischen Delay-Line-Filtern als eine Klasse von optischen Kompensatoren. Die Filtersynthese von solchen Delay-Line-Filtern wird behandelt. Der Zusammenhang zwischen optischen Filtern und digitalen FIR-Filtern mit komplexen Koeffizienten im Zusammenhang mit kohärenter Detektion wird aufgezeigt. Iterative und analytische Methoden, die die Koeffizienten für dispersions- und dispersions-slope-kompensierende Filter produzieren, werden untersucht. Genauso wichtig wie die Kompensation von Dispersion ist die Schätzung der Dispersion eines Signals. Mit Delay-Line-Filtern können die Restseitenbänder eines Signals genutzt werden, um die Dispersion zu messen. Alternativ kann nichtlineare Detektion angewandt werden, um die Pulsverbreiterung, die hauptsächlich von der Dispersion herrührt, zu schätzen. Mit gemeinsamer Dispersionskompensation und Dispersionsmonitoring können Dispersionskompensatoren auf die Signalverzerrungen eingestellt werden. Spezielle Eigenschaften der Filter zusammen mit der analytischen Beschreibung können genutzt werden, um schnelle und zuverlässige Steueralgorithmen zur Filtereinstellung bereitzustellen. Schließlich wurden Prototypen derartiger faseroptischen Kompensatoren von chromatischer Dispersion und Dispersions-Slope hergestellt und charakterisiert. Die Einheiten und ihr Systemverhalten wird gezeigt und diskutiert. / Over the course of the past decades, the global communication system has become a central part of people's everyday lives. Optical communication systems are the technological basis for this development. Only fibers can provide the huge bandwidth that is required. Where the fiber could be regarded as a flat channel for the first optical transmission systems wavelength multiplexing and increasing line rates made it necessary to take more and more physical effects into account. When the line rates are increased to 40 Gbit/s and higher static chromatic dispersion compensation is not enough. The modulation format's intrinsic tolerance for dispersion decreases quadratically with the symbol rate. Thus, environmentally induced chromatic dispersion fluctuations may exceed the dispersion tolerance of the modulation formats. This makes an adaptive dispersion compensation necessary implying also the need for a monitoring scheme to steer the adaptive compensator. Legacy links that are CD-compensated by DCFs can be upgraded with residual dispersion compensators to make them ready for high speed transmission. Optical compensation is independent from the line rate. Hence, increasing the data rates is inherently supported. Optical compensators can be built WDM ready compensating multiple channels at once. The book deals with optical delay line filters as one class of optical compensators. The filter synthesis of such delay line filters is addressed. The connection between optical filters and digital FIR filters with complex coefficients that are used in conjunction with coherent detection could be shown. Iterative and analytical methods that produce the coefficients for dispersion (and also dispersion slope) compensating filters are researched. As important as the compensation of dispersion is the estimation of the dispersion of a signal. Using delay line filters, the vestigial sidebands of a signal can be used to measure the dispersion. Alternatively, nonlinear detection can be used to estimate the pulse broadening which is caused mainly by dispersion. With dispersion compensation and dispersion monitoring, dispersion compensators can be adapted to the signal's impairment. Special properties of the filter in conjunction with an analytical description can be used to provide a fast and reliable control algorithm for setting the filter to a given dispersion and centering it on a signal. Finally, prototypes of such fiber optic chromatic dispersion and dispersion slope compensation filters were manufactured and characterized. The device and system characterization of the prototypes is presented and discussed.

[EN] The processing of radiofrequency signals using photonics means is a discipline that appeared almost at the same time as the laser and the optical fibre. Photonics offers the capability of managing broadband radiofrequency (RF) signals thanks to its low transmission attenuation, a variety of linear and non-linear phenomena and, recently, the potential to implement integrated photonic subsystems. These features open the door for the implementation of multiple functionalities including optical transportation, up and down frequency conversion, optical RF filtering, signal multiplexing, de-multiplexing, routing and switching, optical sampling, tone generation, delay control, beamforming and photonic generation of digital modulations, and even a combination of several of these functionalities. This thesis is focused on the application of vector processing in the optical domain to radiofrequency signals in two fields of application: optical beamforming, and photonic vector modulation and demodulation of digital quadrature amplitude modulations. The photonic vector control enables to adjust the amplitude and phase of the radiofrequency signals in the optical domain, which is the fundamental processing that is required in different applications such as beamforming networks for direct radiating array (DRA) antennas and multilevel quadrature modulation. The work described in this thesis include different techniques for implementing a photonic version of beamforming networks for direct radiating arrays (DRA) known as optical beamforming networks (OBFN), with the objectives of providing a precise control in terrestrial applications of broadband signals at very high frequencies above 40 GHz in communication antennas, optimizing the size and mass when compared with the electrical counterparts in space application, and presenting new photonic-based OBFN functionalities. Thus, two families of OBFNs are studied: fibre-based true time delay architectures and integrated networks. The first allow the control of broadband signals using dispersive optical fibres with wavelength division multiplexing techniques and advanced functionalities such as direction of arrival estimation in receiving architectures. In the second, passive OBFNs based on monolithically-integrated Optical Butler Matrices are studied, including an ultra-compact solution using optical heterodyne techniques in silicon-on-insulator (SOI) material, and an alternative implementing a homodyne counterpart in germanium doped silica material. In this thesis, the application of photonic vector processing to the generation of quadrature digital modulations has also been investigated. Multilevel modulations are based on encoding digital information in discrete states of phase and amplitude of an electrical signal to enhance spectral efficiency, as for instance, in quadrature modulation. The signal process required for generating and demodulating this kind of signals involves vector processing (phase and amplitude control) and frequency conversion. Unlike the common electronic or digital implementation, in this thesis, different photonic based signal processing techniques are studied to produce digital modulation (photonic vector modulation, PVM) and demodulation (PVdM). These techniques are of particular interest in the case of broadband signals where the data rate required to be managed is in the order of gigabit per second, for applications like wireless backhauling of metro optical networks (known as fibre-to-the-air). The techniques described use optical dispersion in optical fibres, wavelength division multiplexing and photonic up/down conversion. Additionally, an optical heterodyne solution implemented monolithically in a photonic integrated circuit (PIC) is also described. / [ES] El procesamiento de señales de radiofrecuencia (RF) utilizando medios fotónicos es una disciplina que apareció casi al mismo tiempo que el láser y la fibra óptica. La fotónica ofrece la capacidad de manipular señales de radiofrecuencia de banda ancha, una baja atenuación, procesados basados en una amplia variedad de fenómenos lineales y no lineales y, recientemente, el potencial para implementar subsistemas fotónicos integrados. Estas características ofrecen un gran potencial para la implementación de múltiples funcionalidades incluyendo transporte óptico, conversión de frecuencia, filtrado óptico de RF, multiplexación y demultiplexación de señales, encaminamiento y conmutación, muestreo óptico, generación de tonos, líneas de retardo, conformación de haz en agrupaciones de antenas o generación fotónica de modulaciones digitales, e incluso una combinación de varias de estas funcionalidades. Esta tesis se centra en la aplicación del procesamiento vectorial en el dominio óptico de señales de radiofrecuencia en dos campos de aplicación: la conformación óptica de haces y la modulación y demodulación vectorial fotónica de señales digitales en cuadratura. El control fotónico vectorial permite manipular la amplitud y fase de las señales de radiofrecuencia en el dominio óptico, que es el procesamiento fundamental que se requiere en diferentes aplicaciones tales como las redes de conformación de haces para agrupaciones de antenas y en la modulación en cuadratura. El trabajo descrito en esta tesis incluye diferentes técnicas para implementar una versión fotónica de las redes de conformación de haces de en agrupaciones de antenas, conocidas como redes ópticas de conformación de haces (OBFN). Se estudian dos familias de redes: arquitecturas de retardo en fibra óptica y arquitecturas integradas. Las primeras permiten el control de señales de banda ancha utilizando fibras ópticas dispersivas con técnicas de multiplexado por división de longitud de onda y funcionalidades avanzadas tales como la estimación del ángulo de llegada de la señal en la antena receptora. En la segunda, se estudian redes de conformación pasivas basadas en Matrices de Butler ópticas integradas, incluyendo una solución ultra-compacta utilizando técnicas ópticas heterodinas en silicio sobre aislante (SOI), y una alternativa homodina en sílice dopado con germanio. En esta tesis, también se han investigado técnicas de procesado vectorial fotónico para la generación de modulaciones digitales en cuadratura. Las modulaciones multinivel codifican la información digital en estados discretos de fase y amplitud de una señal eléctrica para aumentar su eficiencia espectral, como por ejemplo la modulación en cuadratura. El procesado necesario para generar y demodular este tipo de señales implica el procesamiento vectorial (control de amplitud y fase) y la conversión de frecuencia. A diferencia de la implementación electrónica o digital convencional, en esta tesis se estudian diferentes técnicas de procesado fotónico tanto para la generación de modulaciones digitales (modulación vectorial fotónica, PVM) como para su demodulación (PVdM). Esto es de particular interés en el caso de señales de banda ancha, donde la velocidad de datos requerida es del orden de gigabits por segundo, para aplicaciones como backhaul inalámbrico de redes ópticas metropolitanas (conocida como fibra hasta el aire). Las técnicas descritas se basan en explotar la dispersión cromática de la fibra óptica, la multiplexación por división de longitud de onda y la conversión en frecuencia. Además, se presenta una solución heterodina implementada monolíticamente en un circuito integrado fotónico (PIC). / [CAT] El processament de senyals de radiofreqüència (RF) utilitzant mitjans fotònics és una disciplina que va aparèixer gairebé al mateix temps que el làser i la fibra òptica. La fotònica ofereix la capacitat de manipular senyals de radiofreqüència de banda ampla, una baixa atenuació, processats basats en una àmplia varietat de fenòmens lineals i no lineals i, recentment, el potencial per implementar subsistemes fotònics integrats. Aquestes característiques ofereixen un gran potencial per a la implementació de múltiples funcionalitats incloent transport òptic, conversió de freqüència, filtrat òptic de RF, multiplexació i demultiplexació de senyals, encaminament i commutació, mostreig òptic, generació de tons, línies de retard, conformació de feix en agrupacions d'antenes i la generació fotònica de modulacions digitals, i fins i tot una combinació de diverses d'aquestes funcionalitats. Aquesta tesi es centra en l'aplicació del processament vectorial en el domini òptic de senyals de radiofreqüència en dos camps d'aplicació: la conformació òptica de feixos i la modulació i demodulació vectorial fotònica de senyals digitals en quadratura. El control fotònic vectorial permet manipular l'amplitud i la fase dels senyals de radiofreqüència en el domini òptic, que és el processament fonamental que es requereix en diferents aplicacions com ara les xarxes de conformació de feixos per agrupacions d'antenes i en modulació multinivell. El treball descrit en aquesta tesi inclou diferents tècniques per implementar una versió fotònica de les xarxes de conformació de feixos en agrupacions d'antenes, conegudes com a xarxes òptiques de conformació de feixos (OBFN), amb els objectius de proporcionar un control precís en aplicacions terrestres de senyals de banda ampla a freqüències molt altes per sobre de 40 GHz en antenes de comunicacions, optimitzant la mida i el pes quan es compara amb els homòlegs elèctrics en aplicacions espacials, i la presentació de noves funcionalitats fotòniques per agrupacions d'antenes. Per tant, s'estudien dues famílies de OBFNs: arquitectures de retard en fibra òptica i arquitectures integrades. Les primeres permeten el control de senyals de banda ampla utilitzant fibres òptiques dispersives amb tècniques de multiplexació per divisió en longitud d'ona i funcionalitats avançades com ara l'estimació de l'angle d'arribada del senyal a l'antena receptora. A la segona, s'estudien xarxes de conformació passives basades en Matrius de Butler òptiques en fotònica integrada, incloent una solució ultra-compacta utilitzant tècniques òptiques heterodinas en silici sobre aïllant (SOI), i una alternativa homodina en sílice dopat amb germani. D'altra banda, també s'ha investigat en aquesta tesi tècniques de processament vectorial fotònic per a la generació de modulacions digitals en quadratura. Les modulacions multinivell codifiquen la informació digital en estats discrets de fase i amplitud d'un senyal elèctric per augmentar la seva eficiència espectral, com ara la modulació en quadratura. El processat necessari per generar i desmodular aquest tipus de senyals implica el processament vectorial (control d'amplitud i fase) i la conversió de freqüència. A diferència de la implementació electrònica o digital convencional, en aquesta tesi s'estudien diferents tècniques de processament fotònic tant per a la generació de modulacions digitals (modulació vectorial fotònica, PVM) com per la seva demodulació (PVdM). Això és de particular interès en el cas de senyals de banda ampla, on la velocitat de dades requerida és de l'ordre de gigabits per segon, per a aplicacions com backhaul sense fils de xarxes òptiques metropolitanes (coneguda com fibra fins l'aire). Les tècniques descrites es basen en explotar la dispersió cromàtica de la fibra òptica, la multiplexació per divisió en longitud d'ona i la conversió en freqüència. A més, es prese / Piqueras Ruipérez, MÁ. (2016). Photonic Vector Processing Techniques for Radiofrequency Signals [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/63264 / TESIS

In den letzten Jahrzehnten ist das globale Kommunikationssystem in einem immer größerem Maße ein integraler Bestandteil des täglichen Lebens geworden. Optische Kommunikationssysteme sind die technologische Basis für diese Entwicklung. Nur Fasern können die riesige benötigte Bandbreite bereitstellen. Während für die ersten optischen Übertragungssysteme die Faser als "flacher" Kanal betrachtet werden konnte, machen Wellenlängenmultiplex und steigende Übertragungsraten die Einbeziehung von immer mehr physikalischen Effekten notwendig. Bei einer Erhöhung der Kanaldatenrate auf 40 Gbit/s und mehr ist die statische Kompensation von chromatischer Dispersion nicht mehr ausreichend. Die intrinsische Toleranz der Modulationsformate gegenüber Dispersion nimmt quadratisch mit der Symbolrate ab. Daher können beispielsweise durch Umwelteinflüsse hervorgerufene Dispersionsschwankungen die Dispersionstoleranz der Modulationsformate überschreiten. Dies macht eine adaptive Dispersionskompensation notwendig, was gleichzeitig auch Dispersionsmonitoring erfordert, um den adaptiven Kompensator steuern zu können. Vorhandene Links können mit Restdispersionskompensatoren ausgestattet werden, um sie für Hochgeschwindigkeitsübertragungen zu ertüchtigen. Optische Kompensationstechniken sind unabhängig von der Kanaldatenrate. Daher wird eine Erhöhung der Datenrate problemlos unterstützt. Optische Kompensatoren können WDM-fähig gebaut werden, um mehrere Kanäle auf einmal zu entzerren. Das Buch beschäftigt sich mit optischen Delay-Line-Filtern als eine Klasse von optischen Kompensatoren. Die Filtersynthese von solchen Delay-Line-Filtern wird behandelt. Der Zusammenhang zwischen optischen Filtern und digitalen FIR-Filtern mit komplexen Koeffizienten im Zusammenhang mit kohärenter Detektion wird aufgezeigt. Iterative und analytische Methoden, die die Koeffizienten für dispersions- und dispersions-slope-kompensierende Filter produzieren, werden untersucht. Genauso wichtig wie die Kompensation von Dispersion ist die Schätzung der Dispersion eines Signals. Mit Delay-Line-Filtern können die Restseitenbänder eines Signals genutzt werden, um die Dispersion zu messen. Alternativ kann nichtlineare Detektion angewandt werden, um die Pulsverbreiterung, die hauptsächlich von der Dispersion herrührt, zu schätzen. Mit gemeinsamer Dispersionskompensation und Dispersionsmonitoring können Dispersionskompensatoren auf die Signalverzerrungen eingestellt werden. Spezielle Eigenschaften der Filter zusammen mit der analytischen Beschreibung können genutzt werden, um schnelle und zuverlässige Steueralgorithmen zur Filtereinstellung bereitzustellen. Schließlich wurden Prototypen derartiger faseroptischen Kompensatoren von chromatischer Dispersion und Dispersions-Slope hergestellt und charakterisiert. Die Einheiten und ihr Systemverhalten wird gezeigt und diskutiert. / Over the course of the past decades, the global communication system has become a central part of people's everyday lives. Optical communication systems are the technological basis for this development. Only fibers can provide the huge bandwidth that is required. Where the fiber could be regarded as a flat channel for the first optical transmission systems wavelength multiplexing and increasing line rates made it necessary to take more and more physical effects into account. When the line rates are increased to 40 Gbit/s and higher static chromatic dispersion compensation is not enough. The modulation format's intrinsic tolerance for dispersion decreases quadratically with the symbol rate. Thus, environmentally induced chromatic dispersion fluctuations may exceed the dispersion tolerance of the modulation formats. This makes an adaptive dispersion compensation necessary implying also the need for a monitoring scheme to steer the adaptive compensator. Legacy links that are CD-compensated by DCFs can be upgraded with residual dispersion compensators to make them ready for high speed transmission. Optical compensation is independent from the line rate. Hence, increasing the data rates is inherently supported. Optical compensators can be built WDM ready compensating multiple channels at once. The book deals with optical delay line filters as one class of optical compensators. The filter synthesis of such delay line filters is addressed. The connection between optical filters and digital FIR filters with complex coefficients that are used in conjunction with coherent detection could be shown. Iterative and analytical methods that produce the coefficients for dispersion (and also dispersion slope) compensating filters are researched. As important as the compensation of dispersion is the estimation of the dispersion of a signal. Using delay line filters, the vestigial sidebands of a signal can be used to measure the dispersion. Alternatively, nonlinear detection can be used to estimate the pulse broadening which is caused mainly by dispersion. With dispersion compensation and dispersion monitoring, dispersion compensators can be adapted to the signal's impairment. Special properties of the filter in conjunction with an analytical description can be used to provide a fast and reliable control algorithm for setting the filter to a given dispersion and centering it on a signal. Finally, prototypes of such fiber optic chromatic dispersion and dispersion slope compensation filters were manufactured and characterized. The device and system characterization of the prototypes is presented and discussed.