Die vorliegende Arbeit beschreibt die Entwicklung eines Drucksensorkatheters auf Basis von Faser-Bragg-Gittern. Dazu werden der medizinische Hintergrund aus technischer Sicht strukturiert dargelegt und bereits verfügbare Messmethoden für Manometrieuntersuchungen erörtert. Der Stand der Technik bei Faser-Bragg-Gitter basierten Sensoren und deren Auswertegeräten wird im Zusammenhang mit den aus dem medizinischen Hintergrund und dem Vergleich mit den anderen Messmethoden erwachsenden Anforderungen dargestellt. Die Entwicklung eines zweistufigen für die Herstellung mittels Koextrusion geeigneten Mantels für die optischen Fasern wird beschrieben. Mehrere Funktionsmuster für einen Drucksensorkatheter werden experimentell charakterisiert und die Ergebnisse hinsichtlich der Medizineignung bewertet.

Ces trois années de thèse balayent la conception, la fabrication et la caractérisation de lasers III V sur silicium à 1.31 µm pour les data-communications. Le design des sources englobe notamment l’optimisation du couplage entre l’empilement III V et le silicium, effectué grâce à un taper adiabatique, ainsi que l’étude de la cavité laser inscrite, comme le taper, dans le silicium. Trois types de cavités à base de réseaux ont été étudiées: les cavités à contre-réaction distribuée (DFB pour distributed feedback), celles à réseaux de Bragg distribuées (DBR pour distributed Bragg reflector) et enfin celles à réseaux de Bragg échantillonnées (SGDBR pour sampled-grating DBR). Deux solutions ont été abordées concernant les lasers DFB: le réseau, inscrit dans le guide silicium sous la zone de gain, est soit gravé au-dessus du guide Si, soit sur les côtés. La seconde possibilité, appelée ‘DFB lasers couplés latéralement’, simplifie la fabrication et élargit les possibilités de design.Les lasers DFB fabriqués sont très prometteurs en terme de puissance (avec jusque 20 mW dans le guide) ainsi que pour leur pureté spectrale (avec une différence de plus de 50 dB entre le mode principal et le mode suivant). Une accordabilité spectrale de plus de 27 nm a été obtenue en continu avec les lasers SGDBR tout en conservant une très bonne pureté spectrale et une puissance de plus de 7 mW dans le guide. / This 3 years work covers the design, the process and the characterization of III-V on silicon lasers at 1.31 µm for datacommunication applications. In particular, the design part includes the optimization of the coupling between III V and Si using adiabatic tapers as well as the laser cavity, which is formed within the Si. Three types of lasers were studied, all of them based on cavities which consist of gratings: distributed feedback (DFB) lasers, distributed Bragg reflector (DBR) lasers and finally sampled-grating DBR (SGDBR) lasers. Regarding the DFB lasers, two solutions have been chosen: the grating is either etched on top or on the edges of the Si waveguide to form so called vertically or laterally coupled DFB lasers. The latter type, quite uncommon among hybrid III V on Si technologies, simplifies the process fabrication and broadens the designs possibilities.Not only the lasers demonstrated show high output powers (~20 mW in the waveguides) but also very good spectral purities (with a side mode suppression ratio higher than 50 dB), especially for the DFB ones. The SGDBR devices turn out to be continuously tunable over a wavelength range higher than 27 nm with a good spectral purity as well and an output power higher than 7 mW in the waveguide with great opportunities of improvement.

Thanks to its compatibility with the current CMOS technology and its potential of seamless integration with electronics, silicon photonics has been attracting an ever-increasing interest in recent years from both the academia and industry. By applying silicon photonic technology in microwave photonics, on-chip integration of microwave photonic systems could be implemented with improved performance including a much smaller size, better stability and lower power consumption. This thesis focuses on developing silicon-based photonic integrated circuits for microwave photonic applications. Two types of silicon-based on-chip devices, waveguide Bragg gratings and optical micro-cavity resonators, are designed, developed, and characterized, and the use of the developed devices in microwave photonic applications is studied. After an introduction to silicon photonics and microwave photonics in Chapter 1 and an overview of microwave photonic signal generation and processing in Chpater2, in Chapter 3 a silicon-based on-chip phase-shifted waveguide Bragg grating (PS-WBG) is designed, fabricated and characterized, and its use for the implementation of a photonic temporal differentiator is experimentally demonstrated. To have a waveguide grating that is wavelength tunable, in Chapter 4 a tunable waveguide grating is proposed by incorporating a PN junction across the waveguide grating, to use the free-carrier plasma dispersion effect in silicon to achieve wavelength tuning. The use of a pair of wavelength-tunable waveguide gratings to form a wavelength-tunable Fabry-Perot resonator for microwave photonic signal processing is studied. Thanks to its electrical tunability, a high-speed electro-optic modulator, a tunable fractional-order photonic temporal differentiator and a tunable optical delay line are experimentally demonstrated. To increase the bandwidth of a waveguide grating, in Chapter 5 a linearly chirped waveguide Bragg grating (LC-WBG) is designed, fabricated and evaluated. By incorporating two LC-WBGs in two arms of a Mach-Zehnder interferometer (MZI) structure, an on-chip optical spectral shaper is produced, which is used in a photonic microwave waveform generation system based on spectral-shaping and wavelength-to-time (SS-WTT) mapping for linearly chirped microwave waveform (LCMW) generation. To enable the LC-WBG to be electrically tuned, in Chapter 6 a lateral PN junction is introduced in the grating and thus an electrically tunable LC-WBG is realized. By incorporating two tunable LC-WBGs in a Michelson interferometer structure, an electrically tunable optical spectral shaper is made. By applying the fabricated spectral shaper in an SS-WTT mapping system, a continuously tunable LCMW is experimentally generated. Compared with a waveguide Bragg grating device, an on-chip optical micro-cavity resonator usually has a much smaller dimension, which is of help to increase the integration density and reduce the power consumption. Different on-chip optical micro-cavity resonators are studied in this thesis. In Chapter 7, an on-chip symmetric MZI incorporating multiple cascaded microring resonators is proposed. By controlling the radii of the rings, the MZI could be designed to have a spectral response with a linearly-varying free spectral range (FSR), which could be used in photonic generation of an LCMW, and to have a multi-channel spectral response with identical channel spacing, which could be used in the implementation of an independently tunable multi-channel fractional-order temporal differentiator. To further reduce the footprint of an optical micro-cavity resonator, in Chapter 8 an ultra-compact microdisk resonator (MDR) with a single-mode operation and an ultra-high Q-factor is proposed, fabricated and evaluated, and its use for the implementation of a microwave photonic filter and an optical delay line is experimentally demonstrated. To enable the MDR to be electrically tunable, in Chapter 9 an electrically tunable MDR is realized by incorporating a lateral PN junction in the disk. The use of the fabricated MDR in microwave photonic applications such as a high-speed electro-optic modulator, a tunable photonic temporal differentiator and a tunable optical delay line is experimentally demonstrated.

In this thesis, miniaturized wavelength interrogators based on planar lightwave circuits (PLCs) are investigated and developed for the optical fiber sensing applications in the aircraft structural health monitoring (SHM) and optofluidic analysis. Two interrogation systems based on an arrayed waveguide grating (AWG) and an Echelle diffractive grating (EDG) are developed and used to convert the optical sensing signals into strain, temperature, vibration, damage, and humidity information for the aircraft SHM. A fiber Bragg grating (FBG) sensing system using developed interrogators is then demonstrated in a field test for aircraft SHM applications. For optofluidic analysis, a PLCs based optofluidic device consisting of two on-chip lens sets is built to enhance the optical manipulation capability of particles. Then, a solution to a multi-functional Lab-on-a-Chip platform for optofluidic analysis is proposed, which integrates the developed particle maneuvering device, grating-structured sensors, and miniaturized interrogators.

L'industrie nucléaire montre un intérêt croissant pour les technologies basées sur les fibres optiques pour la transmission des données et comme capteurs. Les fibres optiques offrent plusieurs avantages et les capteurs utilisant cette technologie n'ont pas besoin d'alimentation électrique au point de détection, ils ont une réponse rapide et peuvent être facilement multiplexés : dans le cas d'un capteur de température plusieurs thermocouples peuvent être substituées par une seule fibre, diminuant les déchets. Les réacteurs à fission nucléaire constituent un des environnements les plus agressifs : la dose de rayonnement gamma est de l'ordre du GGy avec une forte fluence de neutrons et une température de fonctionnement supérieure à 300°C pour les réacteurs actuels, connus comme de génération III. Ce travail a été réalisé en collaboration avec la société AREVA, industriel français actif dans le domaine de l'énergie, dans le but de réaliser un capteur de température résistant à l'environnement d'un réacteur nucléaire de génération IV, réacteur à neutrons rapides refroidi au sodium liquide. La technologie actuellement utilisée, les thermocouples, présente une dérive de la mesure due au rayonnement et un temps de réponse d'une seconde. Afin de supprimer la dérive, de réduire le temps de réponse et d'augmenter la précision, un capteur de température à réseau de Bragg a été choisi. Pour comprendre le comportement d'un tel système dans un environnement difficile, nous avons utilisé une approche expérimentale basée sur des techniques complémentaires comme l'atténuation induite par le rayonnement, photoluminescence, résonance paramagnétique électronique et spectroscopie Raman / The nuclear industry shows an increasing interest in the fiber optic technology for both data communication and sensing applications in nuclear plants. The optical fibers offer several advantages and the sensors based on this technology do not need any electrical power at the sensing point, they have a quick response and they can be easily multiplexed: in the case of a temperature sensor, several thermocouples can be substituted by a single fiber, resulting in a decrease of the waste material. The fission reactors are a very harsh environment: it is characterized by the highest dose of gamma-rays, of the order of magnitude of GGy, besides a high flux of neutrons and high operating temperature (300°C for the current reactors, known as generation III). This work has been carried out in collaboration with AREVA, a French industrial conglomerate active in the energy domain, with the aim of realizing a temperature sensor resistant to the environment of nuclear reactor of generation IV, in particular a Sodium-cooled Fast Reactor. The currently used technology, the thermocouples, presents a drift of the measurement due to irradiation, that needs a calibration, and a long response time on the order of seconds. In order to remove the drift, to reduce the response time and to increase the precision, a Fiber Bragg Grating temperature sensor was chosen, in regard to all the advantages of the optical fibers. To understand the behavior of such system in a harsh environment, as the nuclear reactor core, we used an experimental approach based on complementary techniques such as radiation-induced attenuation, photoluminescence, electron paramagnetic resonance and Raman spectroscopies

Thesis focuses on the principles and properties of the tilted Bragg fiber gratings. Two models of the principal cladding mode behaviour are proposed and ther respective results compared with experimental data. The experimental setup for the preparation of the tilted gratings is described. The thesis shows the evaluation of the gratings parameters for the set of prepared gratings. Application of the tilted gratings in the sensors is discussed

The thesis deals with the method for the improvement of the measurement accuracy in the optical frequency spectra measurements based on tunable optical filters. The thesis starts with the selection of the proper optical filter that is suitable for accurate light spectrum measurement. The selected filter was then used for the design and realization of the measurement system for the inspection of the fibre Bragg gratings. The system incorporates a reference block for the compensation of environmental influences, an interferometric verification subsystem and a PC - based control software implemented in LabView. The preliminary experimental verification of the measurement principle and the measurement system functionality were carried out on a testing rig with a specially prepared concrete console in the UJV Řež. Advanced tests were conducted on nuclear power plant’s containment shape deformation measurement in Temelin.

The objective of this thesis was to investigate if an optical fiber sensing method with the use of two overlapping fiber Bragg gratings to measure Lamb wave $S_0$ modes in a steel plate, and how it would compare to traditional PZT transducers. A solution was proposed where the use of an optical fiber sensing system was built and took advantage of the strain dependence of a fiber Bragg grating mounted to a steel plate. Together with an overlapping reference fiber Bragg grating, the system can translate strain to light intensity. A method of controlling the Bragg wavelength of the reference fiber Bragg grating to optimize the overlap between the two fiber Bragg gratings, enabling the system to compensate for drift in the sensing fiber Bragg grating. Testing of the system was performed and yielded promising results, being able to measure the Lamb wave signal from the steel plate. The system showed some sensitivity limitations and signal to noise ratio, as well as the software created to compensate for the drift. With the improvement proposed for further work with the system in terms of improving the system's sensitivity, signal to noise ratio and drift control should make the system able to perform at levels as traditional PZT transducers.

No description available.

No description available.