Sensors have become essential elements in human life for safe and comfortable existence in the ever demanding world. Various technologies over decades have contributed in their own way fulfilling innumerable sensing requirements. The discovery of optical sensor technologies has revolutionized the sensing field due to their inherent advantages. Among the large number of fiber optic sensor technologies, FBG based sensors have become widely known and popular within and outside the photonics community and has seen a prominent rise in their utilization. This thesis explores the use of FBG sensors for a wide range of applications scanning across a variety of engineering and medical applications, in the areas of civil engineering, biomechanical engineering, aerospace engineering, geoengineering, etc. It also deals with newer methods of packaging FBG sensors for the measurement of specific engineering parameters like strain, temperature, pressure, displacement and vibration. In the field of civil engineering, FBG sensors are employed for strain sensing on a prism and furthermore tested on a full size brick wallet. During this study, emphasis is made on substituting traditional sensors by specially packaged FBG sensors with the intent of either enhancing the sensing system’s performance or in merging/uniting the inherent advantages of FBG sensors. In the area of biomechanics, a novel sensor methodology using FBG sensors, for measuring surface strains generated on the skin of the calf muscle during various leg exercises is proposed. This methodology is used to address one of the most critical and life threatening issues in long distance air travel, namely the Deep Vein Thrombosis. Further, a FBG sensor based plantar sensing plate, is designed and developed, to measure plantar strain distribution in foot and also to analyze the postural stability. In the field of aerospace engineering, FBG sensors are used for addressing two of the most vital issues; Structural Health Monitoring (SHM) and direct measurement of pressure and temperature on the surface of an aircraft under hypersonic wind flow. Carbon Fiber Composite coupon level testing is carried out to obtain a generic strain calibration factor for the FBG sensor. Further, FBG sensors are exploited for the direct measurement of absolute temperature and pressure on the leeward surface of blunt cone at hypersonic wind speeds. In the domain of geoengineering, the feasibility studies have been undertaken to use a FBG as a seismic sensor and as a bore-well characterizing sensor. A novel FBG seismic sensor package is developed using a single FBG sensor to pick up the seismic waves propagating through the ground generated from earthquakes and ground tremors. Further, FBG sensors are used for measurement of temperature profiles in a bore-well to delineate and characterize the behavior of fractures during seasonal climatic changes. To summarize, the present thesis demonstrates a comprehensive experimental study which bring out the utility of FBG sensors in a variety of challenging applications.

Plants are exposed to a wide range of biotic and abiotic stresses that hinder their growth and reduce crop productivity. In their adaptive response, plants use signaling molecules that are trafficked throughout the plant. This research focuses on the chemical synthesis and assessment of analogs of the plant signal phytosulfokine (PSK, a sulfated pentapeptide), its delivery to plants and its observation using a fiber-optic fluorescence microscope. PSK regulates growth, cell expansion, heat tolerance, and tissue longevity. Analogs of PSK were synthesized using solid-phase peptide synthesis. Pure PSK and TAMRA-labeled PSK were delivered into the wild-type Arabidopsis thaliana Col-0 and a transgenic line expressing PSKR-GFP (PSK receptor – green fluorescent protein). PSKR-GFP could be detected in imaging experiments, but no internalization was observed upon treatment with PSK. Successful implementation of a microscopic approach suited for live plants opens a path to understanding how plants signal and adapt under different stress conditions.

The thesis deals with the possibility of using optical fiber as a sensor. The introduction of the thesis is devoted to the foundations of optics. In addition, the thesis deals with optical interferometry, polarization and dispersion in optical fiber. The main output of the thesis is the comparison of acoustic vibration measurements using interferometric and polarization methods and further measurements on the real route in Brno.

The diploma thesis deals with the assessment of the reliability of processes at the packaging center in the company CommScope Czech Republic s.r.o. The first part of the work is research about options for quality management using ISO 9000 standards, but also TQM approaches. At the same time, methods and analytical techniques are discussed, which will be further used in the practical part of this thesis. The following section introduces CommScope Inc. and its main product - optical fiber. The practical part contains an introduction to the packaging center and its processes, it also describes the analysis of the reliability of the original state and proposals for corrective measures that were designed within the Kaizen event. The rest of the work is then devoted to the implementation of the proposed changes and their economic assessment. Finally, an evaluation of the methods used, the results achieved and other recommendations are given.

The diploma thesis deals with design of the converter card for the precise control of a laser diode. At first, there are described the principles of the laser diode, photodiode and basic functions of optical fiber sensors. Following chapter deals with description of developed converter card. In the diploma thesis are discussed all function blocks of the converter card and they are explained in detail. In the thesis are subsequently tested all problem parts of the converter card for the precise control of the laser diode, such as fast switching of the current flowing through the laser diode and design of the connection for evaluating of current pulse from the sensing photodiode. An integral part of thesis is a description of created printed circuit board and there are described all used layers and devices’ layout on the PCB. Final part of the diploma thesis deals with firmware for the microcontroller, which was made for testing of all function blocks of the converter card for the precise control of a laser diode. At the same time was developed software for PC, which communicates with the converter card via universal serial bus (USB).

This thesis deals with the influence microbending the transmitted signal at the bare optical fiber. Microbending influence on the transmitted signal is investigated in this work by changing the weight, power and water level in the tank by using this test fixture. The results of the experiments are proposed to enter the laboratory tasks to measure the impact microbending the transmitted signal in the subject line fiber-optic sensors (MOES).

La mesure de l'indice de réfraction a été étudiée depuis qu'Ernest Abbé aie initialement conçu un réfractomètre en 1869, appelé le réfractomètre d'Abbé. Depuis lors, de nombreux réfractomètres ont été développés tels que le réfractomètre à prisme optique ainsi que le réfractomètre à fibre optique, en raison de leurs applications étendues pour la détection de divers paramètres physiques, biologiques et chimiques. Récemment, un grand nombre de chercheurs ont mis au point des réfractomètres basés sur des fibres optiques, exploitant des mécanismes tels que la résonance des plasmons de surface (SPR), les interférences multimodes, les fibres à réseaux de Bragg (FBG), les fibres à réseaux à longues périodes (LPG), les fibres optiques coniques et la fibre multimode à gaine dénudée. Les capteurs fibrés sont avantageux grâce à leur immunité contre les interférences électromagnétiques, passivité électrique au niveau de la sonde de détection et potentiel de mesure in situ à long terme. Cette thèse concerne le développement de modèles complets fonctionnels et précis pour les réfractomètres à fibres optiques basés sur la modulation d'intensité optique, en particulier la réfractométrie à fibre multimode à gaine dénudée ainsi que les systèmes hybrides associant fibres monomode et multimode, et un réfractomètre hybride tout fibré utilisant des fibres à cristaux photoniques. L'objectif clé de ce travail est de caractériser les performances de ces réfractomètres à fibres optiques basés sur la modulation d'intensité en termes de réponse en puissance, de sensibilité, de résolution et de dynamique de mesure. Les résultats de simulation qui sont corroborés expérimentalement démontrent que la très grande sensibilité obtenue dans la zone II (c'est-à-dire le régime de détection typiquement utilisé pour mesurer l'indice du milieu supérieur à l'indice de gaine mais inférieur ou égal à l'indice du coeur) pour tous les trois réfractomètres. Cependant, la sensibilité dans la Zone (c’est-à-dire le régime de détection pour lequel l’indice du milieu à mesurer est supérieur à celui du coeur) est très faible. Ainsi, un refractomètre fibré hybride monomode-multimode est utilisé pour améliorer la sensibilité dans la Zone III. D'autre part, la sensibilité pour la zone I (c'est-à-dire le régime de détection pour mesurer l’indice du milieu inférieur à l'indice de la gaine) a été améliorée en augmentant l'absorption des ondes évanescentes à l'aide du réfractomètre hybride tout fibré à base de fibres à cristaux photoniques à coeur solide. En termes d'application réelle du réfractomètre à fibre pour la détection biochimique, une preuve de concept pour un capteur du gaz méthane a été démontrée en utilisant les supramolécules de cryptophane-A qui permettent de piéger les molécules du méthane. Le cryptophane-A incorporé dans un film hôte à base de styrène acrylonitrile (SAN) est appliqué sur la zone dénudée du capteur comme une région fonctionnalisée. L'indice de réfraction de cette couche sensible augmente proportionnellement avec l'augmentation de la concentration du méthane, ce qui induit une variation de la puissance optique transmise dans le capteur fibré. / Refractive index measurement has been studied since Ernest Abbé initially designed a refractometer in 1869, which is named the Abbé refractometer. Since then, numerous types of refractometers have been developed by employing either the optical prism-based refractometer or the optical fiber-based refractometer, due to their wide-ranging applications such as for sensingvarious physical, biological and chemical parameters. Recently, a large number of researchers have been developing refractometers based on optical fibers, exploiting mechanisms such as surface plasmon resonance (SPR), multimode interference, fiber Bragg gratings (FBG), long period gratings (LPG), tapered optical fibers, and striped-cladding multimode fibers (MMF), for their advantages in immunity against electromagnetic interference, electrical passivity at the sensing probe, and capability to long term in-situ measurement. This thesis concerns the development of comprehensively functional and accurate models for optical fiber refractometers based on optical intensity modulation, in particular for stripped-cladding MMF refractometry as well as hybrid systems involving a combination of single-mode-multimode fiber refractometery and the all-fiber hybrid refractometer using photonic crystal fibers. A key objective of this work is to characterize the performance of these intensity-based optical fiber refractometers in terms of their power response, sensitivity, resolution, and dynamic range. The simulation results which are corroborated experimentally demonstrate very high sensitivity being obtained in Zone II (i.e. the sensing regime typically employed for measuring a sensing medium index higher than the cladding index but less than or equal to the core index) for all three types of refractometers. However, the sensitivity in Zone III (i.e. the sensing regime for which the sensing medium index is higher than the core index) is very low. A hybrid single-mode fiber - multimode fiber configuration is used to improve the sensitivity in Zone III. On other hand, the sensitivity for Zone I (i.e. the sensing regime typically employed for measuring a sensing medium index lower than the cladding index) has been improved by increasing evanescent wave absorption using the all-fiber hybrid refractometer based on solid-core photonic crystal fibers. As a further potential of the fiber refractometer for applications in biochemical sensing, the proof-of-concept for a methane gas sensor has been demonstrated using supramolecular cryptophane-A which enables to trap the methane molecules. Cryptophane-A incorporated into a functionalized film of StyreneAcrylonitrile (SAN) host is applied to a de-cladded region of the sensor as the sensitive region. The refractive index of this functionalized layer increases proportionally with increasing methane concentration, subsequently inducing variations in the transmitted optical power along the fiber sensor.

Bohrlochintegrität ist unerlässlich für die erfolgreiche und nachhaltige Produktion und Injektion von Fluiden aus Reservoirgesteinen, wie beispielsweise bei der Nutzung von Kohlenwasserstoffen, Geothermie oder Standorten für geologische Speicherung. Um die Integrität einer Bohrung über seine Lebenszeit zu gewährleisten, ist vor allem eine erfolgreiche primäre Komplettierung nötig. Besonders die Zementation der Rohre stellt dabei ein großes Risiko dar, weil durch die natürlichen Gegebenheiten im Bohrloch viele Faktoren Einfluss auf die Zusammensetzung und Verteilung der Zementsuspension haben. Diese Studie untersucht das Monitoring-potenzial von faseroptischer ortsverteilter Dehnungsmessung DSS (distributed strain sensing). Ergänzend zu faseroptischer ortsverteilten Temperaturmessung DTS (distributed temperature sensing), welche seit mehr als zwei Jahrzehnten in der Industrie Anwendung findet, kann jeder Ort einer Glasfaser zusätzlich Informationen über den mechanischen Spannungszustand geben. Experimentelle und analytische Arbeiten wurden durchgeführt, um die Auswirkung von Laständerungen auf einer Faser zu quantifizieren. Desweiteren wurde der Einfluss komplexer mehrschichtiger Bohrlochkabel auf Dehnungsmessergebnisse untersucht. Ein faseroptisches Messkabel wurde im Zuge dieser Arbeit im Ringraum entlang der Produktionsrohrtour einer Bohrung installiert. Die gemessenen Geländedaten zeigen Ergebnisse aus zwei Arbeitsschritten der Fertigstellung der Bohrung - der Filterverkiesung und der Zementation. Aufgrund der Dichtedifferenz von Kies und Bohrspülung wurde am Kabel ein Dehnungseffekt gemessen. Die Teufe, in welcher der Dehnungseffekt auftritt, korreliert mit Wireline Gamma-Gamma-Dichtedaten, welche im gleichen Zeitfenster gemessen wurden. Die anschliessende Kompaktion des Kieskopfes wurde durch das Glasfaserkabel in Form einer zunehmenden mechanischen Belastung erfasst. Während der anschliessenden Zementation der Rohrtour wurde ein Dehnungseffekt in der Mischzone von Flüssigkeiten mit unterschiedlichen rheologischen Eigenschaften gemessen. Anhand eines Experiments konnte bestätigt werden, dass fluidrheologische Parameter (wie die Fluidviskosität) mit einem faseroptischen Messkabel quantifiziert werden können. Hierfür werden Fluidscherspannungen gemessen, welche durch das Fliessen von Fluiden an der Kabeloberfläche hervorgerufen werden (amtliches Zeichen zur Patentanmeldung: EP 19171265.2). DSS-Messungen erweiten das Verständnis von Fluidverdrängungsvorgängen in Bohrlöchern und ermöglichen eine Beurteilung von Komplettierungsvorgängen in Echtzeit. / Borehole integrity is fundamental for the successful and sustainable utilization of hydrocarbons, geothermal energy and sites for geological storage. The success of the primary well completion is necessary to ensure the integrity of a well over its lifetime. In particular, the casing cementation represents a great risk because many factors have an influence on the composition and distribution of the cement suspension due to the natural conditions in the borehole. This study investigates the monitoring potential of fiber-optic distributed strain sensing (DSS) using a measurement cable which is installed in the annulus of a well. Similar to distributed temperature sensing (DTS), which is used for temperature monitoring in industry applications for more than two decades, fibers additionally convey information about their mechanical stress state. Laboratory as well as analytical work was performed to quantify the effect of load changes on a fiber. In addition, the influence of complex multilayered downhole cable on the strain response is examined. The presented field data shows results from two stages of the well completion - the gravel packing and the cementation. Due to the difference in density of gravel and drilling fluid, a deformation is measured on the cable. The depth at which the stretching effect occurs correlates with wire-line gamma-gamma density data measured in the same time window. The subsequent compaction of the gravel head, which was not revealed by the logging measurement, was detected by the fiber optic cable in the form of an increasing mechanical load on the cable. During cement pumping, fluid shear stresses create a measurable load on the cable, especially in the mixing zone of liquids with dfferent rheological properties. Based on this observation, an experiment was designed and conducted which aims at measuring fluid rheological parameters such as fluid viscosity. For this purpose, the fluid shear stresses acting on the fiber optic sensing cable in the flow path are measured (patent application number: EP 19171265.2). DSS measurements extend the understanding of fluid displacements in wellbores and allow an assessment of well completion process in real time.

In der medizinischen Diagnostik, Bioverfahrenstechnik und Umwelttechnik besteht ein steigender Bedarf an kompakten Analysegeräten für die schnelle Vor-Ort-Detektion spezifischer biochemischer Substanzen. Im Rahmen der Arbeit wurde daher ein neuartiger faseroptischer Sensor entwickelt, der in der Lage ist kleinste Brechzahländerungen, z.B. durch molekulare Bindungsprozesse, zu detektieren. Die hohe Empfindlichkeit an der vergoldeten Spitze der Sensorfaser beruht auf der Oberflächenplasmonenresonanz (SPR) einer einzelnen Mantelmode, die durch ein langperiodisches Fasergitter (LPG) ermöglicht wird. Die Übertragungsfunktion des Sensors wurde unter Verwendung eines Schichtwellenleitermodells schnell und präzise modelliert. Es konnte gezeigt werden, dass in einem wässrigen Umgebungsmedium die höchste Empfindlichkeit im Spektralbereich um 660 nm unter Annahme einer rund 35~nm dicken und 2~mm langen Goldbeschichtung erreicht wird. Weiterhin wurde nachgewiesen, dass mit einer intermediale Schicht aus Cadmiumsulfid die SPR der Mantelmode in einen höheren Spektralbereich verschoben und damit die Empfindlichkeit deutlich verbessert werden kann. Um eine geringe Polarisationsabhängigkeit des Sensors sicherzustellen, wurde ein nasschemisches Abscheidungsverfahren für die allseitige Goldbeschichtung der Sensorfaser entwickelt. Die spezifischen optischen Eigenschaften dieser Abscheidungen wurden mit Hilfe von LPGs untersucht, die durch eine spezielle UV-Belichtung hergestellt wurden. Die Experimente ergaben, dass die komplexe Permittivität nasschemischer Abscheidungen mit Schichtdicken oberhalb von 50~nm mit aufgedampften Goldschichten vergleichbar ist. Die Verluste der adressierten Mantelmoden wurden mit einer äquivalenten Sensoranordnung aus zwei identischen LPG untersucht. Dabei konnte ein Skalierfaktor abgeleitet werden, der die effiziente Berechnung der Mantelmodendämpfung erlaubt. Es wurde nachgewiesen, dass die Brechzahlauflösung etablierter volumenoptischer SPR-Sensoren mit einer einfachen Transmissionsmessung an einer geeigneten Wellenlänge erreicht werden kann. Die äußerst kompakte Sensorfläche des faseroptischen Sensors ermöglicht darüber hinaus die Untersuchung deutlich kleinerer Probenvolumina ohne ein zusätzliches mikrofluidisches System zu benötigen. Es wurde gezeigt, dass sekundäre Brechzahländerungen aufgrund von Temperaturschwankungen oder unspezifische Ablagerungen durch eine differentielle Auswertung zweier identischer Sensoren kompensiert werden können. Die verbleibende Querempfindlichkeit wird durch die Polarisationsabhängigkeit der Sensoren bestimmt. Die geringste Querempfindlichkeit konnte daher mit einer homogenen nasschemischen abgeschiedenen Sensorfläche nachgewiesen werden. / Compact analysis devices which facilitate the rapid detection of specific biochemical substances are in increasing demand in the fields of point-of-care medical diagnostics, bioprocess engineering and environmental engineering. The aim of this work was therefore to design a novel fiber-optic sensor able to detect small refractive index changes such as those caused by molecular binding processes. The high level of sensitivity at the gold-plated tip of the sensor fiber stems from the surface plasmon resonance (SPR) of a single cladding mode, which is the result of a long-period fiber grating (LPG). The transfer function of the sensor was calculated quickly and accurately using a slab waveguide model. It was observed that the highest level of sensitivity in an aqueous ambient medium is achieved at a wavelength of 660 nm assuming a gold coating of 35 nm in thickness and 2 mm in length. Furthermore, it was demonstrated that an intermedial cadmium sulfide layer shifts the SPR of the cladding mode towards higher wavelengths, thus leading to significantly enhanced sensitivity. An electroless plating process for the omnidirectional deposition of gold on the sensor fiber was developed in order to minimize the sensor\'s dependency on polarization. The specific optical properties of the gold layer deposited were investigated with the aid of LPGs fabricated using a special UV exposure method. The experiments showed the complex permittivity of electroless platings with a thickness of over 50 nm to be comparable with that of evaporated gold layers. The losses of the addressed cladding modes were investigated using an equivalent sensor setup consisting of two identical LPGs. This facilitated the determination of a scaling factor enabling the effcient calculation of cladding mode attenuation. It was demonstrated that it is possible to obtain the refractive index resolution of established volume optical SPR sensors with the aid of simple transmission measurements at a specific wavelength. Moreover, the extremely compact sensing area of the fiber-optic sensor enables the investigation of smaller sample volumes without the need for an additional microfluidic system. Secondary refractive index changes caused by temperature fluctuations or unspecific binding events can be compensated for by means of the differential interrogation of two identical fiber-optic sensors. The residual cross sensitivity is determined by the polarisation dependency of the sensor. The lowest cross sensitivity was therefore demonstrated in combination with a homogeneous electroless plated sensor surface.

Plants secrete peptide ligands and use receptor signaling to respond to stress and control development. Understanding the signaling mechanisms and associated molecular trafficking is key to improving plant health and productivity for food, fiber and energy applications. However, one of the challenges to elucidating communication pathways in plants is to study the trafficking of molecules and signals iteratively and non-destructively. This study focuses on using fiber-optic fluorescence microscopy to image live plants iteratively and non-destructively after delivering both labeled and unlabeled phytosulfokine (PSK) into the plant. PSK is a sulfated peptide hormone involved in the regulation of plant cell division and growth via specific receptors, PSKRs. It also plays a role in regulating how plants are able to tolerate stress conditions. The microscope provides two-color (FITC/TRITC) optics and provides high-resolution (3–5 µm) epifluorescence micrographs via a 1-m coherent imaging fiber and a GRIN objective lens. To obtain high-quality images, the fiber was mounted either to a conventional upright microscope body equipped with a leaf compressor, or to a leaf clip with 5-axis positioning (X–Y–Z plus pitch and yaw) mounted on an extensible arm. PSK and TAMRA-labelled PSK were delivered into the roots of various Arabidopsis thaliana genotypes (wt; receptor-deficient: pskr1/pskr2; and tagged receptor overproducing: PSKR1‑GFP), and their movement in roots and leaves was tracked with the fiber-optic fluorescence microscope. Peptide trafficking was successfully observed in live plants non- destructively, confirming that PSK is mobile in both wt and receptor-deficient plants. Preliminary results suggest that the level of receptor PSKR1 may change in response to PSK, and that levels of PSKR1, PSKR2 or both may impact the trafficking of PSK. Understanding how PSK is trafficked in plants will offer insights into how we can improve plants health and productivity.