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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
31

OPTICAL COMMUNICATIONS TESTBED FOR THE EXPLOITATION OF LUMINESCENCE EMISSIONS OF SOLAR CELLS FOR OPTICAL FREQUENCY IDENTIFICATION (OFID)

Samuel Denton (8817131) 08 May 2020 (has links)
<div>The purpose of this thesis was to investigate the possibility of Optical Frequency Identification (OFID) technology being used as a communication pathway for devices in LiFi systems that serve to open alternative transmission paths for Internet-of-Things infrastructure. LiFi or light-fidelity, plays off the concept of wireless-fidelity, commonly known as WiFi, and follows the trend of moving to higher frequencies within the electromagnetic spectrum. LiFi lies within the visual light and infrared wavelength range, which can be referred to as the nanometer wave range. The developed optical communication testbed is a proof of concept showing that OFID technology, enabled by Gallium Arsenide solar cell emission, can communicate with Visual Light Communication (VLC) systems. The scope of the work entails the development of a testbed for a custom optical communications testbed for OFID linked to VLC communication by sending transmissions via powerline modulation. An optical receiver circuit was developed and tested, and integration and testing for powerline communication and LED luminaire were successful. Manchester encoded data was sent at 4800 bit rate optically from an infrared light source, received by the developed receivers and was decoded. Information was successfully transmitted over powerline from computer terminal to LED luminaire output at 2400, 3600, 4800, 7200, and 9600 bit rate. Integration of these communication links did not occur due to Purdue University closure of campus related activities from COVID-19.<br></div>
32

Frequency Comb Experiments and Radio Frequency Instrumentation Analysis for Optical Atomic Clocks

Ryan J Schneider (14187461) 29 November 2022 (has links)
<p>Space-based global navigation and precision timing systems are critical for modern infrastructure. Atomic clock technology has increased the precision of these systems so that they are viable for military operations, navigation, telecommunications, and finance. Advances in optical atomic clocks, based on optical frequencies, provide an opportunity for even more precise timing. Therefore, developments in chip-scale optical atomic clock technologies could lead to increased and more wide-spread application of this precision timing. One component of the optical atomic clock is the optical frequency comb which serves as an interface between optical and microwave frequencies. This thesis will cover experiments related to these optical frequency combs. A 2$\mu$m fiber laser was developed in order to test second harmonic devices required to stabilize an optical frequency comb. The laser was then employed to measure the operating wavelengths and efficiencies of non-linear devices. In addition, an analysis of the radio frequency instruments used to evaluate microwave outputs was conducted to determine whether a digital signal analyzer (oscilloscope) or an analog electronic spectrum analyzer provides more accurate results for optical frequency comb based experiments.</p>
33

Two-Photon Direct Frequency Comb Spectroscopy of Rubidium

Chen, Sophia Lee 29 May 2012 (has links)
No description available.
34

Modelagem numérica de uma fibra óptica microestruturada para sensoriamento distribuído de pressão

Miraglia, Rodrigo Cesar Ribeiro 20 August 2010 (has links)
Made available in DSpace on 2016-03-15T19:37:31Z (GMT). No. of bitstreams: 1 Rodrigo Cesar Ribeiro Miraglia.pdf: 2147088 bytes, checksum: 67087392fe4b03bb24d9a164fd92ceed (MD5) Previous issue date: 2010-08-20 / Fundo Mackenzie de Pesquisa / Sensors based on optical fibers are being increasingly used in hostile environments for measuring pressure, temperature, stress, chemical and biological parameters, etc. These sensors have the advantage of having reduced size and weight, immunity to electromagnetic interference, of being chemically inert, and also allowing the distributed measurement of the respective parameter along the fiber. Microstructured optical fibers have characteristics that are relevant to sensing applications, such as freedom of design of their internal structure obtained by varying the diameter of the holes and the distances between them, among other parameters, which is not applicable in conventional optical fibers. The present work aims to use a microstructured optical fiber as a distributed sensor for hydrostatic pressure, using the POTDR (Polarization Optical Time-Domain Reflectometry) and the OFDR (Optical Frequency-Domain Reflectometry) measurement techniques. The application of hydrostatic pressure on the fiber changes its birefringence and, consequently, the evolution of the states of polarization, which is the parameter monitored by the techniques. By monitoring the changes of these states, it is possible to infer the changes in applied pressure. The study is undertaken via simulations and analysis, both performed in the software MatLab. / Sensores baseados em fibras ópticas vêm sendo cada vez mais utilizados em ambientes hostis para medição de pressão, temperatura, stress, análise química e biológica, etc. Esses sensores têm a vantagem de possuírem tamanho e peso reduzidos, imunidade à interferência eletromagnética, de serem quimicamente inertes, e também permitirem a medição distribuída do parâmetro a ser analisado ao longo da fibra. As fibras ópticas microestruturadas possuem características relevantes na aplicação de sensoriamento, tal como a liberdade de construção de sua estrutura interna variando o diâmetro dos buracos e a distância entre eles, entre outros parâmetros, que não são aplicáveis em fibras ópticas convencionais. Este trabalho tem como objetivo estudar uma fibra óptica microestruturada como sensor distribuído de pressão hidrostática, utilizando as técnicas de medição POTDR (Polarization Optical Time-Domain Reflectometry) e OFDR (Optical Frequency-Domain Reflectometry). A aplicação de pressão hidrostática sobre a fibra altera sua birrefringência e, consequentemente, a evolução do seu estado de polarização, sendo este último o parâmetro monitorado pelas técnicas. Analisando-se a mudança deste estado, pode-se inferir a mudança de pressão aplicada. O estudo é realizado através de simulações e análises efetuadas no software MatLab.
35

Nonlinear dynamics of Kerr optical frequency combs / Dynamique non-linéaire des peignes de fréquences optiques de Kerr Nonlinear dynamics of Kerr optical frequency combs

Balakireva, Irina 09 December 2015 (has links)
La présente thèse est consacrée à l’étude des peignes optiques de Kerr dans les résonateurs àmodes de galerie, au sein desquels la lumière peut être excitée par pompage externe. L’effet Kerrexistant dans ces résonateurs engendre des modes latéraux équidistants (dans le domaine spectral)de part et d’autre du mode excité, c’est à dire un peigne de fréquence. Cette thèse est diviséeen trois chapitres. Le premier est dédié à l’introduction de la génération de ces peignes et leurapplications. Le deuxième chapitre présente l’analyse de l’équation de Lugiato-Lefever, décrivantde manière analytique le système, et conduit à la construction de deux diagrammes de bifurcationpour les dispersions normale et anomale. Ils sont tracés en fonction des deux seuls paramètresexpérimentalement contrôlables une fois le résonateur fabriqué : la puissance du laser et sondécalage de fréquence. Ces diagrammes indiquent les plages de paramètres pour lesquels une,deux, ou trois solutions existent ainsi que leur stabilité. Les simulations numériques renseignentle type exact de solution associée à chaque aire (notamment les solitons brillants et sombres, lesbreathers, les peignes optiques de Kerr de premier et deuxième ordre, et un régime chaotique) ; cesdiagrammes indiquent donc les paramètres du laser à choisir afin de générer la solution souhaitée.Le troisième chapitre est dédié aux peignes de Kerr optique secondaires, lignes additionnelles dansle domaine spectral générées entre les lignes du peigne principal. Ils apparaissent en dispersionanormale, lorsque la quantité de photon pompe excède un seuil dit de second ordre, qui a étédéterminé numériquement. / This thesis is dedicated to the study of the Kerr optical frequency combs in whispering gallery moderesonators, where the light can be excited by the extern pump. Due to the Kerr effect existing in theseresonators, the quasi-equidistant lines in the spectral domain are generated around the excited mode,that is the frequency comb. This thesis is devided in three chapters. The first one is dedicated to theintroduction of the Kerr comb generation and their applications.The second one presents the analysisof the Lugiato-Lefever equation used for the analytical study of the system, leading to the constructionof two bifurcation diagrams for the normal and anomalous dispersions. They are plotted for twoparameters, which can be controlled during experiments once the resonator has been fabricated,which are the pump power of the laser and its frequency detuning. These diagrams show the areas ofthe parameters for which one, two, or three solutions exist and their stability. The additional numericalsimulations show the exact type of the solution in each area (such as the bright and dark solitons,the breathers, the primary and secondary Kerr combs and chaotical regimes), finally these diagramsshow the parameters of the laser needed to be choosen for the generation of the desired solution.The third chapter is dedicated to the secondary Kerr combs, which are the additional lines generatedbetween the lines of the primary comb. They appear in the anomalous dispersion regime, when thequantity of the pump photons crosses the second-order threshold, which has been found numerically.
36

Quantum dot based mode locked lasers for optical frequency combs / Lasers à blocage de modes à base de boîtes et bâtonnets quantiques pour les peignes de fréquences optiques

Calo, Cosimo 18 December 2014 (has links)
Les peignes de longueurs d'onde, produisant des dizaines de porteuses optiques régulièrement espacées à partir d'une seule source laser, présentent un grand intérêt pour les systèmes de communication à haut débit. Ce travail de thèse porte sur les peignes générés par les diodes laser à blocage de modes basées sur des nanostructures semi-conductrices à basse dimensionnalité. Dans cette étude, les performances en verrouillage de modes de lasers Fabry-Pérot mono-section basés sur différents systèmes de matériaux sont comparées sur la base de la largeur du spectre optique d'émission et de la capacité à produire des impulsions courtes à faible gigue temporelle. En remarquant que les lasers à base de bâtonnets quantiques InAs sur InP présentent de meilleures caractéristiques par rapport aux autres matériaux examinés, leurs propriétés spécifiques en termes de stabilité des peignes de fréquences optiques et de chirp des impulsions sont étudiées plus en détail. Le chirp est d'abord étudié par la technique FROG (frequency-resolved optical gating). Ensuite, la dispersion chromatique du matériau laser est évaluée afin de vérifier si elle peut expliquer les grandes valeurs de chirp mesurées par FROG. Pour cela la technique de réflectométrie optique dans le domaine fréquentiel est utilisée et ses capacités uniques de mesure ont été étudiées et validées. Enfin, ces lasers sont employés avec succès pour les transmissions haut débit à l'aide de la technique de modulation optique OFDM (orthogonal frequency-division multiplexing) en détection directe. Débits de l'ordre du térabit par seconde, ainsi que le faible coût de l’architecture du système, sont très prometteurs pour les data centers / Optical frequency combs, generating tens of equally spaced optical carriers from a single laser source, are very attractive for next-generation wavelength division multiplexing (WDM) communication systems. This PhD thesis presents a study on the optical frequency combs generated by mode-locked laser diodes based on low-dimensional semiconductor nanostructures. In this work, the mode-locking performances of single-section Fabry-Pérot lasers based on different material systems are compared on the basis of the optical spectrum width, the timing jitter and pulse generation capabilities. Then, noticing that InAs quantum dashes grown on InP exhibit on average better characteristics than other examined materials, their unique properties in terms of comb stability and pulse chirp are studied in more detail. Laser chirp, in particular, is first investigated by frequency resolved optical gating (FROG) characterizations. Then, chromatic dispersion of the laser material is assessed in order to verify whether it can account for the large chirp values measured by FROG. For that, a high sensitivity optical frequency-domain reflectometry setup is used and its measurement capabilities are extensively studied and validated. Finally, the combs generated by quantum dash mode-locked lasers are successfully employed for high data rate transmissions using direct-detection optical orthogonal frequency division multiplexing. Terabit per second capacities, as well as the low cost of this system architecture, appear to be particularly promising for future datacom applications
37

High Precision Optical Frequency Metrology

Das, Dipankar 05 1900 (has links)
Precise measurements of both absolute frequencies and small frequency differences of atomic energy levels have played an important role in the development of physics. For example, high precision measurements of absolute frequencies of the 2S½ → 2P ½ transition (D1 line) of alkali atoms form an important link in the measurement of the fine structure constant, α. Similarly, precise interferometric measurements of the local gravitational acceleration (g) rely on the knowledge of the absolute frequencies of the 2S½ → 2P 3/2 transition (D2line) in alkali atoms. Difference frequency measurements of hyperfine structure and isotope shifts of atomic energy levels provide valuable information about the structure of the nucleus, which in turn helps in fine tuning the atomic wave functions used in theoretical calculations. The work reported in this thesis starts with the development and refinement of high precision measurement of absolute frequencies using a ring-cavity resonator. The measurement technique is relatively simple and cost-effective, but the accuracy is comparable to that achieved with the frequency comb technique (10¯11) when the accuracy is limited by the natural linewidth of the transition being measured. The technique combines the advantages of using tunable diode lasers to access atomic transitions with the fact that the absolute frequency of the D2 line in87Rb is known with an accuracy of 6 kHz. A frequency-stabilized diode laser locked to this line is used as a frequency reference, along with a ring-cavity resonator whose length is locked to the reference laser. For a given cavity length, an unknown laser locked to an atomic transition has a small frequency offset from the nearest cavity resonance. We use an acousto-optic modulator (AOM) to compensate for this frequency offset. The measured offset is combined with the cavity mode number to obtain a precise value for the frequency of The unknown laser. We have used this technique for absolute frequency measurements Of the D lines in133Cs and 6,7Li, and the 398.8nm line in Yb. We have also developed a technique to measure the ‘difference frequency’ of atomic energy levels using a single diode laser and an AOM. In this technique, the laser is first locked to a given hyperfine transition. The laser frequency is then shifted using the AOM to another hyperfine transition and the AOM frequency is locked to this difference. Thus the AOM frequency directly gives a measurement of the hyperfine interval. Applying this AOM technique we have measured the hyperfine interval of the D1 lines of all alkali atoms with high precision. We have further developed a technique of coheren-tcontrol spectroscopy (CCS) using co-propagating control and probe beam that is useful for highresolution spectroscopy. In this technique, the probe beam is locked to a transition and its absorption signal is monitored while the control beam is scanned through neighbouring transition. As the control comes into resonance with another transition, the probe absorption is reduced and the signal shows a Doppler free dip. This technique allows us to resolve transitions that are otherwise swamped by crossover resonances in conventional saturated absorption spectroscopy (SAS). We have applied this technique to measure hyperfine intervals in the D2 line of several alkali atoms. Thus, we were able to do high-precision measurements of both absolute and difference frequency of atomic transitions. The precision of the absolute frequency measurement is finally limited by the accuracy of 6 kHz with which the reference frequency is known. The nearby two photon transition in Rb, i.e. the 5S1/2→5D3/2 transition at 778 nm, is known with an accuracy of 1 kHz. In future, we hope to improve the accuracy of our technique using this transition as the reference. This thesis is organized as follows: In Chapter1,we give a brief introduction to our work.. We review the importance of frequency measurements and precision spectroscopy, followed by a comparison of the frequency comb and our ring cavity technique. In Chapter2, we describe measurements of the absolute frequency of the D lines of 133Cs using the ring cavity. We give a detailed discussion of the technique, the Possible sources of errors, and ways to check for the errors. The measurement of the absolute frequency of the D lines of Cs allows a direct comparison to frequency comb measurements, and thus acts as a good check on our technique. In Chapter 3, we describe the absolute frequency and isotope shift measurements in the 398.8 nm line in Yb. We probed this line by frequency doubling the output of a tunable Ti:Sapphire laser. We obtained< 60 kHz precision in our measurements and were able to resolve several discrepancies in previous measurements on this line. In Chapter 4, we describe the measurement of hyperfine structure in the D1 lines of alkali atoms. We used conventional saturated-absorption spectroscopy in a vapor cell to probe different hyperfine transitions and then used our AOM technique to measure the hyperfine interval with high precision. In Chapter 5 we discuss our measurements of hyperfine structure in the D2 lines of several alkali atoms. In the case of 23Na and 39K, the closely-spaced hyperfine transitions are not completely resolved in conventional saturatedabsorption spectroscopy due to the presence of cross over resonances. We have used coherent control spectroscopy to obtain crossover-free spectra and then measured the hyperfine intervals using an AOM. This technique was also used for high resolution spectroscopy in the D2 line of 133Cs. Finally, we describe our measurements of hyperfine structure in the D2 line of Rb using normal saturated absorption spectroscopy. Chapter 6, describes the relative and absolute frequency measurements in the D lines of6,7 Li at 670nm. High-precision measurements in lithium are of special interest because theoretical calculations of atomic properties in this simple three electron system are fairly advanced. Lithium spectroscopy poses an experimental challenge and we describe our efforts in doing highresolution spectroscopy on this system. Chapter 7 describes the hyperfine spectroscopy on the1P 1 state of 173Yb. Measurement of hyperfine structure in 173Yb has a problem because two of the hyperfine transitions overlap with the transition in 172Yb. In our earlier work (described in chapter 4), we had solved this problem by using multipeak fitting to the partially resolved spectrum. Here, we directly resolve the hyperfine transitions by using transverse laser cooling to selectively deflect the 173Yb isotope. In Chapter 8 , we give a broad conclusion to the work reported in this thesis and suggest future avenues of research to continue the work commenced here.
38

Capteurs de corrosion à fibre optique pour la surveillance répartie d’ouvrages en béton armé / Distributed corrosion sensing in reinforced concrete structures by optical fiber sensing

Ali Alvarez, Shamyr Sadat 19 September 2016 (has links)
La corrosion des armatures de renforcement des structures en béton représente un enjeu socio-économique majeur. Sa détection et le suivi de son évolution constituent un défi pour la recherche appliquée. Les techniques standards non destructives de détection de corrosion mettent en œuvre des procédés indirects tels la mesure d’impédance, de potentiels, ou par ultrasons. Leurs capacités d’auscultation sont limitées dans l’espace (notamment en profondeur), leur coût reste élevé dans un contexte de maintenance périodique et elles conduisent à des paramètres d’interprétation complexe. Des progrès sont nécessaires dans la détection et l’analyse fiable de la progression des processus de corrosion. Dans ce travail, nous présentons une nouvelle méthode pour détecter la corrosion et le suivi de son évolution, basée sur l’observation directe des changements intervenant à l’interface fer-béton par Capteur à Fibre Optique (CFO). L'attaque par corrosion de la surface de l'armature dépend de plusieurs paramètres électrochimiques (température, pH, carbonatation, présence de chlorures, contamination biologique, etc.). Deux comportements mécaniques à l'interface fer-béton sont distingués. Dans le premier cas (carbonatation), le produit d'oxydation du métal reste à l'interface et augmente la pression interne, pouvant conduire à la fissuration de la couche de béton extérieure. Dans le second cas (piqures), les ions métalliques sont évacués hors de la structure avec comme conséquence une réduction de section des barres d'armature (affaiblissement du renforcement). Un CFO innovant est proposé dans le but de localiser et quantifier les deux types de corrosion précités. Le principe consiste à observer l’impact direct de la corrosion sur l’état de déformation d’une fibre optique préalablement précontrainte par construction. Deux procédés métrologiques sont étudiés : Bragg et réflectométrie fréquentielle (Optical Frequency-Domain Reflectometry - OFDR). Des tests de corrosion accélérée montrent la faisabilité du procédé. Une procédure de fabrication simplifiée et à coût optimisé est proposée pour la surveillance in situ et répartie des structures de génie civil, dans une perspective future de maintenance conditionnée. / Corrosion of reinforced bars (rebars) in concrete structures remains a major issue in civil engineering works, being its detection and evolution a challenge for the applied research. Usual non-destructive corrosion detection methods involve impedance, potential or ultra-sonic indirect measurements of complex interpretation. Besides, they are restricted to near-surface examinations and the maintenance cost is still high (scheduled maintenance). Many efforts remain to be done to survey the onset and progression of corrosion processes in a reliable way. In this work, we present a new methodology to detect the onset of corrosion and to monitor its evolution, based on the direct observation of rebar–concrete interface changes by the use of an Optical Fiber Sensor (OFS). The corrosion attack over rebar surface depends on several physical, chemical and electrochemical parameters (temperature, pH, presence of chlorides/CO2, biological contamination, etc.). Two types of mechanical behavior and described. In the first case (carbonation), metal oxidation products stay at the interface and increase internal pressure, potentially leading to a crack of the external concrete layer. In the second case (pitting), metal ions are evacuated out of the structure, leading to a reduction of the rebar section (structural weakness). An innovative sensor design is proposed with the purpose of localizing and quantifying the amount of both corrosion types. The basic principle consists in measuring the impact of corrosion over the state of strain of a prestressed optical fiber. Two metrological techniques are used: Fiber Bragg Grating (FBG) and Optical Frequency-Domain Reflectometry (OFDR). Accelerated corrosion tests were performed in electrolytic solutions for both kinds of corrosion types (pitting and carbonation) and provide a proof-of-concept for the technique. A low-cost, simplified manufacturing procedure is proposed with the aim to provide distributed and in situ Structural Health Monitoring (SHM), suitable for future Condition-Based Maintenance (CBM) of civil engineering concrete structures.
39

Optical Frequency Domain Interferometry for the Characterization and Development of Complex and Tunable Photonic Integrated Circuits

Bru Orgiles, Luis Alberto 28 March 2022 (has links)
[ES] Esta tesis aborda la caracterización de circuitos fotónicos integrados (PIC) usando interferometría óptica en el domino de las frecuencias (OFDI). OFDI tiene una implementación razonablemente simple e interroga al dispositivo bajo test (DUT) proporcionando su respuesta en el dominio del tiempo, en la que los distintos caminos ópticos seguidos por la luz se manifiestan en contribuciones que contienen información de posición, amplitud y fase. Junto con un "setup" OFDI construido en nuestros laboratorios y estructuras de test integradas que involucran anillos resonantes, interferómetros, etc., proponemos e implementamos técnicas para obtener parámetros ópticos cruciales tales como el índice de grupo, dispersión cromática, rotación de polarización y pérdidas de propagación en guías de onda. También para caracterizar acopladores ópticos. Se realizan evaluaciones directas de fase óptica en diferentes experimentos para, entre otras aplicaciones, caracterizar efectos de calor en chips. En la culminación de la tesis, se aborda la integración conjunta de los interferómetros de OFDI junto con el DUT, concibiéndolo como una estructura de caracterización integrada. El uso de guías de onda integradas proporciona una alta estabilidad y adaptación al DUT, además de un mecanismo inherente de compensación de la dispersión. Se realiza un análisis y prueba de concepto experimental caracterizando un "arrayed waveguide grating" en tecnología de nitruro de silicio. Seguidamente, se da un paso adelante proponiendo una arquitectura interferométrica de tres brazos novedosa que permite reducir la complejidad de la medida. Se lleva a cabo una validación experimental amplia usando distintos equipos de laboratorio, acoplamiento horizontal y vertical al chip, y diferentes DUTs en tecnologías de nitruro de silicio y "silicon-on-insulator". / [CAT] Aquesta tesi aborda la caracterització de circuits fotònics integrats (PIC) usant interferometria òptica al domini de les freqüències (OFDI). OFDI té una implementació raonablement simple i interroga el dispositiu sota test (DUT) proporcionant la seva resposta en el domini del temps, en què els diferents camins òptics seguits per la llum es manifesten en contribucions que contenen informació de posició, amplitud i fase. Juntament amb un "setup" OFDI construït als nostres laboratoris i estructures de test integrades que involucren anells ressonants, interferòmetres, etc., proposem i implementem tècniques per obtenir paràmetres òptics crucials com ara l'índex de grup, dispersió cromàtica, rotació de polarització i pèrdues de propagació en guies d'ona. També per caracteritzar acobladors òptics. Es fan avaluacions directes de fase òptica en diferents experiments per, entre altres aplicacions, caracteritzar efectes de calor en xips. A la culminació de la tesi, s'aborda la integració conjunta dels interferòmetres d'OFDI juntament amb el DUT, concebent-ho com una estructura de caracterització integrada. L'ús de guies d'ona integrades proporciona una alta estabilitat i adaptació al DUT, a més d'un mecanisme inherent de compensació de la dispersió. Es realitza una anàlisi i prova de concepte experimental caracteritzant un "arrayed waveguide grating" en tecnologia de nitrur de silici. Seguidament, es fa un pas avant proposant una arquitectura interferomètrica de tres braços nova que permet reduir la complexitat de la mesura. Es du a terme una validació experimental àmplia usant diferents equips de laboratori, acoblament horitzontal i vertical al xip, i diferents DUTs en tecnologies de nitrur de silici i "silicon-on-insulator". / [EN] This PhD thesis covers the characterization of complex photonic integrated circuits (PIC) by using Optical Frequency Domain Interferometry (OFDI). OFDI has a fairly simple implementation and interrogates the device under test (DUT) providing its time domain response, in which the different optical paths followed by light manifest in contributions with position, amplitude and phase information. Together with a working OFDI setup built in our laboratory and integrated test structures involving devices such as ring resonators, interferometers, etc., we propose and implement techniques to get crucial optical parameters such as waveguide group refractive index, chromatic dispersion, polarization rotation, and propagation loss. Also, to characterize optical couplers. Direct optical phase assessment is made in different experiments permitting, amongst others, the characterization of on-chip heat effects. In the culmination of the thesis, the co-integration of the OFDI interferometers with the DUT is addressed, conceiving it as an integrated characterization structure. The use of integrated waveguides provide high stability and adaptation to the DUT, as well as an inherent dispersion de-embedding mechanism. It is provided analysis and experimental proof of concept with an arrayed waveguide grating as DUT in a silicon nitride platform. A considerable leap forward is then taken by proposing a novel three-way interferometer architecture, reducing the measurement complexity. Wide experimental validation is carried out using different laboratory equipment, horizontal and vertical chip coupling, and different DUTs in silicon nitride and silicon-on-insulator. / Bru Orgiles, LA. (2022). Optical Frequency Domain Interferometry for the Characterization and Development of Complex and Tunable Photonic Integrated Circuits [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/181635
40

QUANTUM AND CLASSICAL OPTICAL FREQUENCY COMBS FOR METROLOGY AND NETWORKING APPLICATIONS

Suparna Seshadri (19163878) 26 July 2024 (has links)
<p><br></p><p dir="ltr">Over the past decade, optical frequency combs have spurred significant advancements in both classical ultrafast optics and quantum optics. My research contributes to these two fields, catering to applications in precision metrology and optical networking. In the domain of quantum optics, the study delves into biphoton frequency combs with time-energy entanglement, employing novel electro-optic modulation schemes to enhance sensitivity and enable precise measurements of temporal correlations. Additionally, Bell states, a crucial class of entangled quantum bases, are generated in the frequency domain, showcasing their utility in delay metrology and quantum cryptographic protocols. </p><p dir="ltr">In the realm of classical optical frequency combs, this work explores dynamic steering of pulsed optical beams, holding promise for applications in imaging and remote sensing. The concept of time-efficient dynamic beam steering using a spatial array of optical frequency combs is elucidated and experimentally demonstrated through the utilization of a high-resolution spectral disperser, specifically a virtually imaged phased array (VIPA). Furthermore, integrated photonic designs featuring wavelength-selective switches and spectral dispersers are proposed to enable a versatile on-chip implementation of the beam steering approach. In sum, this research leverages the capabilities of classical and quantum optical frequency combs, with implications for emerging applications such as distributed sensing, quantum networking, and light detection and ranging (LIDAR).</p>

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