L'oscillateur optoélectronique (OEO) a été introduit pour la première fois en 1996 par S. Yao et L. Maleki, en tant qu'oscillateur microondes à très faible bruit de phase et obtenu par synthèse directe. Les développements de l'OEO concernent les applications en photonique microondes, télécommunications optiques, radar et traitement du signal. Mais l'OEO devrait aussi pouvoir être utilisé dans le domaine des capteurs. Dans cette thèse nous étudiants plusieurs aspects de l'OEO pour son application à la mesure d'indice de réfraction d'un liquide. Compte tenu de sa structure l'OEO dépend fortement des conditions ambiantes d'utilisation. S'il n'est pas bien optimisé ni contrôlé, il ne peut pas fonctionner correctement sur une longue durée. Nous avons étudié les influences de la température sur le modulateur électrooptique (EOM) et sur le comportement global de l'OEO. Un contrôle de température réduit de façon significative le phénomène de dérive de l'EOM. Afin de la supprimer complètement, nous avons mis au point une instrumentation construite autour d'une carte DSP, permettant de détecter et compenser la dérive du point de fonctionnement optique de l'EOM tout en contrôlant simultanément sa température. Une première technique est basée sur un signal de test, basse fréquence, appliqué à l'électrode DC du modulateur. Une deuxième solution consiste à travailler sur la puissance optique en sortie du modulateur. En combinant les deux on peut profiter des avantages de ces deux méthodes. Utilisant ainsi l'OEO nous avons testé plusieurs configurations pour mesurer l'indice de réfraction de quatre solutions chimiques bien connues, nous avons obtenu une variance de 3 pour mille. Les résultats sont en assez bon accord avec les publications correspondantes. Enfin nous avons aussi introduit une nouvelle méthode pour améliorer les mesures d'indice de réfraction faites à long terme en suivant, grâce à un analyseur vectoriel de réseau, les évolutions au cours du temps du temps de propagation dans la fibre optique. En introduisant à partir de cette mesure une correction aux mesures de la fréquence d'oscillation il est possible de réduire les fluctuations de cette fréquence à seulement 606 Hz, sur une durée de 62 h, ce que l'on peut comparer aux 8 GHz de l'oscillateur. Ainsi le rapport signal à bruit, peut être grandement amélioré lors de la mesure d'indice de réfraction et il doit être possible de diminuer la limite de détection des variations de l'indice de réfraction au cours du temps. / The optoelectronic oscillator (OEO) was first introduced in 1996 by S. Yao and L. Maleki as a very low phase noise microwave oscillator working in direct synthesis. The OEO developments concern applications in microwave photonics, optical telecommunication, radar and high speed signal processing systems but it should also be used in the sensing domain. In this thesis, we study several aspects to apply the OEO to liquid refractive index measurement. Because of its structure the OEO is very dependent on the ambient conditions. If the OEO is not optimized and controlled, it cannot operate well for long duration. We have analyzed the influences of temperature on the electrooptic modulator (EOM) and the global OEO behavior. Temperature control can significantly reduce the drift phenomena of the EOM. In order to totally remove this drift, we have developed a complete digital system, based on a DSP kit, to detect and compensate automatically the EOM optical bias point drift and to control simultaneously its temperature. The first technique is based on a dither signal at low frequency, injected to DC electrode of the EOM. The second one is based on the average optical output power of the EOM. A combination of these two techniques can take advantages from both of them. Using like that the OEO, we have tested several configurations to measure the refractive index of four classical chemical solutions leading to a standard deviation of 3 per thousand. The results are in rather good agreement with previous publications. Finally, we have introduced a new method to improve the long-term refractive index measurement by monitoring, with a vector network analyzer, the variations of the optical delay in the fiber loop of the OEO. Introducing by this way a correction to the long-term frequency measurement it is possible to reduce the oscillation frequency fluctuations to only 606 Hz, compared to the 8 GHz of the oscillator, for a duration of 62 hours. Therefore the signal-to-noise ratio in the refractive index measurement can be enhanced and so the detection resolution of the refractive index variations during time.

El silicio es un material de suma importancia en microelectronica y en fotonica. Las propiedades semiconductoras del silicio estan detras de los conceptos que gobiernan el funcionamiento de la mayoría de los dispositivos electronicos como los diodos y los transistores. El concepto de integracion ha permitido procesar dispositivos muy pequeños, llegando a alcanzar un tamaño nanometrico. El alto indice de refraccion del silicio permite confinar la luz en estructuras de tamaño micrometrico. Este es el caso de dispositivos fotonicos tales como las guias de onda y las cavidades. Usualmente, tanto los dispositivos fotonicos como los electronicos estan basados en la tecnologia planar, es decir poseen una topologia plana, siendo esto una fuente de perdidas. Es bien conocido que las cavidades esfericas confinan la luz con mas eficiencia que las cavidades planares. Esta tesis trata sobre el desarrollo de un nuevo tipo de microparticulas esfericas que llamamos Coloides de Silicio. Debido a su forma esferica, su alto indice de refraccion y su suave superficie, estas particulas funcionan como microcavidades opticas con modos resonantes bien definidos en el infrarrojo cercano. La tesis reporta sobre la sintesis, y las propiedades estructurales y opticas de los coloides de silicio con diametro entre 0.5 y 3.5 micrometros. Los coloides de silicio pueden facilitar el desarrollo de microcavidades de alto factor de calidad con alta eficiencia de confinamiento de la luz, y permitir la integracion de dispositivos electronicos y fotonicos tales como una union p-n en una sola particula coloidal. Esta tesis reporta tambien sobre los coloides de silicio como elementos integrantes de las Esponjas Fotonicas, las cuales estan formadas por una red desordenada de microesferas de silicio de diferentes tamaños, e interaccionan con la luz fuertemente en un ancho rango de longitudes de onda. / Tymczenko, MK. (2010). Photonic microcavities and photonic sponges based on silicon colloids [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/8425 / Palancia

The aim of the thesis is to put a transparent scaled PMMA model of the pressure swirl nozzle into operation, which includes, the selection of working fluids and the preparation of a test set to allow measurements using optical methods (LDA, PDA, PIV, high-speed visualization). The theoretical part describes the basic theory of atomization, optical measurement methods and deals with the problems of optical transition in optically complex systems. It also includes an extensive search for transparent liquids and materials of enlarged models that have been used in experiments, which often aim to match light refractive indices between these materials. In the practical part, attention is paid to the preparation of the test set and tests of chemical effects of several selected liquids on PMMA material are conducted, including a summary of experience with their use, as there was a permanent damage to the material. Several LDA measurements followed, using kerosene, p-cymene, 1-bromonaphthalene and water, evaluated the effect of the refractive index difference on the results. It turned out that no observable influence occurred if the refractive index difference between the nozzle material and the liquid was small. In addition, a visualization of internal flow through a high-speed camera was made. The practical part closes the static pressure measurement in the nozzle chamber, where the pressure ratio was measured on the walls of the chamber as well as on its axis. The measurement confirmed that the pressure on the chamber walls is constant and varies with the distance from the chamber axis.

This master’s thesis deals with the design of methodology for measurement of refractive index and thickness of living cells by coherence-controlled holographic microscope. The theoretical part summarises the holographic microscopy and its development at IPE FME BUT in Brno. The thesis focuses on the multimodal holographic microscope, its description, the principle, the procedure of work and data processing. Confocal microscopy is also described, which serves to compare the acquired values with the proposed methodology. The last part of the theoretical part deals with the testing of statistical hypotheses, which is needed for the processing of measured data. Experiments were designed for the verification of methodology for determination of the refractive index and cell thickness. The experimental part of the thesis deals with the sample preparation and measurement. The procedure and results of the proposed experiments and their evaluation follows.

This diploma thesis is about creating a program to model turbulent cells of different sizes on the chosen transmission path. The initial part of the work is devoted to the formation of atmospheric turbulence and the mathematical description of the extent of turbulence and its effect on optical waves. The methods of the turbulence generation and their physical description of formation are described below. The practical part is devoted to the created program in the MATLAB.

People around the globe are immensely trying to connect using light as carrier due to its low power consumption and high data transfer rates. Sound and microwaves are examples of other carriers that can be used, although they aren't nearly as efficient as light. A method of communicating is using light beneath the surface of the water. As the depth of the water increases, the temperature, pressure, and salinity of the water are changed. The refractive index of water is determined by the combination of all of these variable parameters. The goal of this thesis is to establish a relationship between changes in water temperature, salinity, and pressure resulting in changes of the refractive Index of the sea water. This thesis will demonstrate an empirical model of travelling the ultraviolet wave under sea water. We are acknowledging all of the properties that are change as the depth of the water is increasing. MATLAB was used to create a simulation of this scenario. Based on previous model of light traveling which covers the wavelengths between 400-700 nm, we have extended the model to ultraviolet range of light (200-400 nm).We design an experimental set up according to sea water parameters and then the experimental results are compared to the simulation results. The comparison shows the validity of our extension model.

This thesis deals with a theoretical analysis and experimental verification of a new method for the refractive index of air measurement. This method uses a combination of laser and low-coherence interferometry. The experimental setup is based on the Michelson interferometer equipped with a double-spaced glass cell. The optical path difference between the inner and outer part of the cell that is proportional to air refractivity is estimated using two low-coherence interference signals. These signals are analysed in the frequency domain which results in the dependence of the phase change caused the by air on vacuum wavelength. This dependency is fitted by a theoretical function based on Edlén's equations in order to calculate the phase difference for laser wavelength. This value is then made more accurate utilising two laser interference signals and used for the air refractive index calculation. The new method was experimentally verified and compared to two different techniques. Moreover, the measurement uncertainty was evaluated.

The aim of the diploma thesis is theoretical analysis of optical fiber sensory sensing using coherent and incoherent interferometry, creation of simulation models of interferometers and their practical measurement. The first part deals with the description of basic physical principles and interferometers. In the second part the thesis deals with the description and design of optical microphones, which are based on the principles of physical interferometers Michelson and Mach - Zehneder interferometer. Both models are simulated in the VPIphotonics simulation environment. In the third part of the thesis, both models are assembled and measured. The last part of the thesis presents the differences between the interferometers and the results of the measurements.

We report on a new framework for preparing high-refractive index polymeric materials which combines the selective thiol radical mono-addition to phenyl-acetylene derivatives with hyperbranched architectures. Using this strategy we have synthesized a series of linear and hyperbranched polyvinyl sulfide (PVS) materials, employing different dithiol (A₂ and A'₂) and di- and trialkyne (B and B₃) monomers. The process requires only a simple radical initiator, such as AIBN, in lieu of expensive or toxic catalysts and this chemistry produces polymers in high yield (up to 96%) and high molecular weight (up to 123 000 g mol⁻¹). The polymers are optically transparent, thermally stable (up to 420 °C) and readily form highquality films. The end group composition of the hyperbranched materials can be easily adjusted by changing the A₂/B₃ feed ratio. The sulfur incorporation and conjugation resulting from thiol–yne coupling with selective mono-addition results in materials with high refractive indices in the visible and IR region (nD = 1.68–1.75) and optical dispersions as low as 0.004. Moreover, we demonstrate that the hyperbranched architecture produces materials with better performance in terms of light reflection and chromatic dispersion compared to linear structures.

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.