Дисертації з теми "OPO Fibre"

Les recherches industrielles ou académiques autour laser délivrant des impulsions ultracourtes reposent de plus en plus sur la technologie des lasers à fibre. Elles s’appuient sur les avantages intrinsèques des systèmes à fibre, tels que leur stabilité, compacité, l'excellente qualité modale du faisceau délivré, leur robustesse et leur facilité d'utilisation. Au cours de ce travail, nous avons réalisé l’étude détaillée d’un laser à fibre délivrant des impulsions picosecondes fonctionnant dans un régime de dispersion normale (ANDi). Ce laser a par la suite été déployé pour étudier de la génération paramétrique dans une fibre à cristal photonique. Nous avons tout d’abord développé une source laser à fibre de haute puissance délivrant des impulsions picosecondes dont on peut accorder à la fois la longueur d'onde centrale et la largeur spectrale. La source développée autour d’une cavité en anneau comprend la combinaison d’une fibre d'ytterbium à grande surface modale du type « rod-type », une fente et un réseau de diffraction en transmission. À la longueur d'onde centrale de ∼ 1030 nm et à un taux de répétition de 78 MHz, ce laser délivre des impulsions picosecondes avec une puissance moyenne allant jusqu'à 25 W. La durée des impulsions peut être ajustée en continu entre ∼ 1,8 ps et ∼ 4,5 ps alors que l'énergie des impulsions varie entre ∼ 320 nJ et ∼ 225 nJ. Nous avons également démontré que la longueur d'onde centrale des impulsions laser peut-être finement réglée entre ∼ 1010 nm à ∼ 1060 nm tout en s’assurant que l'énergie de l'impulsion est supérieure ∼ 150 nJ. Nous avons également développé un modèle numérique pour rendre compte de l'ensemble de nos données expérimentales. Nos simulations sont en bon accord avec nos résultats expérimentaux. Les impulsions délivrées par cette source ont été utilisées pour étudier et réaliser un oscillateur paramétrique optique dans une fibre optique. Les ondes signal et idler générées résultent d’un mélange paramétrique à quatre-onde induit dans une fibre à cristal photonique. Cet OPO à fibre est simplement résonnant pour l’onde signal. L'efficacité de conversion pour l’onde signal est proche de 20 %. Le profil de dispersion spectrale de la fibre à cristal photonique et l’accordabilité spectrale de notre laser de pompe nous ont permis de générer des ondes du signal (resp. idler) comprises respectivement entre ∼ 770 nm et ∼ 1000 nm ( ∼ 1130 nm et ∼ 1590nm) lorsque la longueur d'onde des impulsions pompe est ajustée entre ∼ 1024 nm et ∼ 1059 nm
Ultrashort laser pulses in both industrial and research applications progressively rely on fiber laser technology, guided by its intrinsic benefits, for instance, stability, compact nature, excellent beam quality, robustness, and easy operation. In this work, a detailed study has been done to investigate picosecond fiber laser working in an all-normal-dispersion (ANDi) regime for the application of parametric generation in photonic crystal fiber. In summary, we have developed a high-power fiber laser source delivering picosecond pulses with tunability both in central wavelength and spectral width. It incorporates a combination of a large-mode-area rod-type ytterbium fiber, a slit, and a transmission grating inside the ring laser cavity configuration. At the central wavelength of ∼ 1030 nm and with a repetition of 78 MHz, this laser delivers picosecond pulses with an average power of up to 25 W. The pulse duration can be continuously adjusted from ∼ 1.8 ps to ∼ 4.5 ps and pulse energy from ∼ 320 nJ and ∼ 225 nJ, respectively. Additionally, we have also demonstrated that the central wavelength of the laser pulse can be finely tuned from ∼ 1010 nm to ∼ 1060 nm while keeping the pulse energy above ∼ 150 nJ. We have also proposed a numerical model to account for the ensemble of our experimental data and the simulations are in good agreement with the experimental data. The output of this fiber oscillator is propagated through the photonic crystal fiber for the parametric generation of the signal (higher frequencies than the pump) and idler (lower frequencies than the pump). The fiber OPO singly-resonant cavity was built in such a way that only signal wavelengths are allowed to propagate through it. The conversion efficiency for the signal was close to 20 % in the fiber OPO. Based on the dispersion profile of the photonic crystal fiber and our homebuilt tunable pump laser, the signal wavelength (resp. idler) was tuned from ∼ 770 nm to ∼ 1000 nm (∼ 1130 nm to ∼ 1590nm) for the corresponding pump wavelengths of ∼ 1024 nm to ∼ 1059 nm

Les états comprimés de lumière sont des états quantiques qui peuvent être utilisés dans de nombreux protocoles pour le calcul quantique et la communication quantique. Leur génération en laboratoire a déja été étudiée au paravant, mais ils manquent en general encore de compacité et de praticitalité pour une intégration facile dans des expériences plus grandes. Cette thèse considère deux expériences: celle menée en France, le miniOPO; et celle menée en Australie, le SquOPO. Les deux sont de nouvelles conceptions de sources compactes d' état de lumière comprimé dans l'optique d'une integration future. Le miniOPO est une cavité linéaire d'une longueur de 5 mm entre l'extrémité d'une fibre et un miroir incurvé avec un cristal de PPKTP de 1 mm à l'intérieur. Le vide comprimé généré dans cette cavité est couplé dans la fibre pour pouvoir être envoyé vers un systeme de mesure, (dispositif homodyne) ou vers une plus grande expérience. La cavité est résonnante pour la frequence de lumiere comprimé et pour celle de la pompe. Le systeme est verrouillé en fréquence en utilisant des effets auto-verrouillant du à l'absorption de la pompe dans le cristal. La double résonance est obtenue en changeant la température du cristal. Deux fibres différentes ont été testées dans cette expérience, une fibre mono-mode standard, et une fibre photonique mono-mode avec un diametre de mode plus important. Le vide comprimé obtenu est encore assez faible (0.5dB avec la fibre standard et 0.9dB pour la fibre photonique), mais un certain nombre d'améliorations sont étudiées pour augmenter ces niveaux dans l'avenir. Le SqOPO est une cavité carrée monolithique dans un cristal de niobate de lithium. En utilisant quatre réflexions total internes sur les quatre faces du crystal, il est possible de definir un mode optique de cavité pour la frequence du vide comprimé et celle du mode de la pompe. La lumière est couplée dans le résonateur en utilisant une frustration de la réflexion interne par des prismes. La distance entre les prismes et le résonateur défini la force du couplage de la lumière, ce qui nous permet de contrôler la la finesse de la lumière dans le résonateur. En utilisant des prismes biréfringents, il est possible de controler indépendamment la finesse des deux fréquences dans le résonateur pour atteindre un régime optimum. Comme pour le MiniOPO, La fréquence de resonance de la cavité est verouillé grace à l' absorption de la lumière de pompage dans le résonateur, ce qui permet d' atteindre l'auto-verrouillage. La double résonance est contrôlée par le réglage de la température du cristal. et la position des prismes. Nous avons démontré 2.6dB de vide comprimé avec ce système. Encore une fois, la quantité de compression est faible, mais des améliorations qui pourraient être mises en œuvre dans l'avenir sont discutées
Squeezed states of light are quantum states that can be used in numerous protocols for quantum computation and quantum communication. Their generation in labora- tories has been investigated before, but they still lack compactness and practicality to easily integrate them into larger experiments. This thesis considers two experiments: one conducted in France, the miniOPO; and one conducted in Australia, the SquOPO. Both are new designs of compact sources of squeezed states of light towards an integrated system. The miniOPO is a linear cavity of 5mm length between the end of a fiber and a curved mirror with a PPKTP crystal of 1mm inside it. The squeezing generated in this cavity is coupled into the fiber to be able to be brought to a measurement device (homodyne) or to a larger experiment. The cavity is resonant for the squeezed light and the pump light, and locked in frequency using self-locking effects due to absorption of the pump in the crystal. The double resonance is achieved by changing the temperature of the crystal. Two different fibers have been tested in this experiment, a standard single-mode fiber and a photonic large core single-mode fiber. The squeezing obtained is still quite low (0.5dB with the standard fiber and 0.9dB for the photonic fiber) but a number of ameliorations are investigated to increase these levels in the future. The SqOPO is a monolithic square cavity made in a Lithium Niobate crystal using four total internal reflections on the four faces of the square to define an optical mode for the squeezed mode and the pump mode. The light is coupled in the resonator using frustrated internal reflection with prisms. The distance between the prisms and the resonator defined the coupling of the light, which allows us to control the finesse of the light in the resonator and by using birefringent prisms it is possible to tune independently the two frequencies in the resonator to achieve an optimal regime. The frequency of the light is locked using absorption of the pump light in the resonator to achieve self-locking, and double resonance is controlled by tuning the temperature of the crystal. We demonstrated 2.6dB of vacuum squeezing with this system. Once again, the amount of squeezing is low, but ameliorations that could be implemented in the future are discussed

Les fuites de méthane soulèvent à la fois des problématiques environnementales et sécuritaires, particulièrement dans l'industrie pétrolière. Le contrôle de panaches en temps réel permettrait de prévenir d'éventuels drames humains et catastrophes écologiques. Dans ce contexte, un volet du projet NAOMI, impliquant TOTAL E&P et l'ONERA, vise à développer des instruments de télédétection capables de localiser (résolution spatiale de l'ordre de 100 m) et de caractériser les fuites majeures de méthane à une distance de sécurité (1 km) sur le terrain. Pour répondre à ce cahier des charges, ce travail de thèse décrit l'étude, la conception et la caractérisation d'un prototype lidar fibré, émettant dans le domaine proche infrarouge (1.65 µm) : VEGA (VEnt et GAz). L'utilisation d'un schéma de détection hétérodyne permet en effet d'envisager un système bi-fonction, capable de mesurer simultanément la vitesse du vent via le décalage Doppler (utile pour évaluer la dispersion d'un panache) et la concentration de méthane par la technique DIAL. Au laboratoire, des mesures intégrées (cible à 2.2 km) ont démontrée, pour la première fois à notre connaissance avec un lidar hétérodyne, la sensibilité de l'instrument au méthane. L'exactitude de ces estimations du niveau atmosphérique (1.95 ± 0.26 ppm en 1 s d'accumulation) s'avère satisfaisante pour l'application visée (impliquant une concentration très supérieure). La participation à une campagne de mesure en 2018 (à Lacq) a démontré le bon comportement du prototype lidar sur le terrain, justifiant le choix d'une architecture tout-fibré. L'utilisation de plusieurs stratégies de mesures (simples, multi lignes de visée, multi spectrale) a également souligné la capacité de VEGA à identifier et quantifier la concentration au sein de lâchers de méthane contrôlés, à environ 200 (résolution de 30 m) dans une gamme étendue de débit de 0.1 à 300 g.s-¹. Au cours de la campagne, les erreurs aléatoires observées, de l'ordre ± 10 - 100 ppm en 1 sec d'accumulation s'avèrent conformes aux modèles théoriques. Des extrapolations de la précision à des distances supérieures montrent toutefois la nécessité d'améliorer le prototype (au travers de pistes réalistes, identifiées dans ce document) pour atteindre une portée kilométrique. Finalement, les bases pour l'estimation autonome du flux, combinant les mesures gaz et vent , ont été posées
Especially in the oil and gas industry, methane leaks threaten both safety and environment. The real-time monitoring of such plumes could prevent potential human or ecological disasters. In this context, one part of NAOMI project, involving TOTAL and ONERA, aims to develop remote sensing tools capable of locating (with a spatial resolution of 100 m) and characterize major methane leaks from a safety distance (1 km) on the field. To meet these specifications, the present work describes the study, design and performances assessments of a fiber lidar emitting in the near infrared (1.65 µm) : VEGA ("VEnt et GAz", French for "wind and gaz"). The choice of a coherent detection scheme allows to consider a dual-function system, able to simultaneously measure wind speed with Doppler shift (useful to assess plume dynamic) and methane concentration with the DIAL technique. In the lab, integrated-path measurements (target at 2.2 km) have shown, a first to our knowledge with a coherent lidar, VEGA's sensibility to methane. The accuracy of ambient level measurements (1.95 ± 0.26 ppm for 1 s averaging) is seen to be satisfying for the target application (involving much higher concentration). During a field campaign in 2018 (Lacq, France), the lidar has shown a good thermo-mechanical behaviour, justifying the choice of an all-fibered architecture. The use of several measurement procedures (simple, several laser lines of sight, several wavelengths) allowed VAGA to identify controlled methane leaks at 200 m (30 m resolution) in a wide range of flow rates (from 0.1 to 300 g.s-¹. During the campaign, the observed statistical errors, in the ±10 to 100ppm range for 1 s averaging, are in good agreement with theoretical models. Assessing these errors at greater distances shows, nonetheless, a need to improve the lidar (through mentioned improvement tracks) to reach an adequate precision at 1 km. Eventually, the basis for autonomous flow rate estimation, combining both wind and gas data, had been presented

Amplificadores a fibra dopada com érbio de dupla passagem (DP-EDFA) contendo fibras compensadoras de dispersão (DCF) são estudados nesta tese. Os DP-EDFAs são uma alternativa para amplificadores de baixo custo e bom desempenho, sobretudo para utilização em redes metropolitanas. Devido a sua estrutura de dupla passagem, outras funções podem ser facilmente inseridas em seu circuito óptico, incrementando sua funcionalidade e reduzindo o custo envolvido. Considerando ainda que a compensação da dispersão é crítica para sistemas WDM de alta velocidade, um interessante tópico de investigação, que será bastante explorado nesta tese, refere-se a embutir uma fibra compensadora de dispersão dentro no circuito do DP-EDFA. Estudos experimentais são conduzidos, mostrando as vantagens e os problemas associados a algumas topologias de circuitos de DP-EDFAs. Um circuito original de DP-EDFA contendo DCF é proposto e caracterizado em termos de ganho e figura de ruído para diversas aplicações multicanal e multibanda dentro do espectro de transmissão da fibra óptica. Caracterizações sistêmicas em termos de taxa de erro de bit são também conduzidas
Double pass erbium doped fiber amplifiers (DP-EDFA) with an embedded dispersion compensation fiber are studied in this work. DP-EDFA is a cost-effective alternative for optical amplifiers, yet preserving good optical performance, mainly for use in metropolitan networks. Due to its double pass circuit, others functions beyond amplification can be inserted within the amplification circuit, increasing its capabilities and decreasing the involved cost. Considering that dispersion compensation is very critical for high-speed DWDM systems operating with standard single mode fiber, a timely topic of investigation concerns the embedding of the high insertion loss DCFs (dispersion compensating fibers) into optical amplifier configurations. Experimental studies are conducted first showing the advantages and impairments associated with DP-EDFAs circuits using DCFs. Next, a DP-EDFA proposed in this work is characterized in terms of gain and noise figure for several applications in multichannel and multiband network topologies. Systemic characterization in terms of bit error rate is also conducted, evaluating the performance of the proposed DP-EDFA using DCF

Cette thèse en deux parties porte sur le développement de sources lasers nano et picosecondes et leurs applications. La première partie présente l'étude, et la réalisation d'une chaîne amplificatrice laser nanoseconde pour l'allumage de turbomoteurs. Après avoir présenté les performances et l'évolution de cette chaîne seront présentes les résultats des campagnes d'essais réalisées sur une chambre de combustion sur un banc d'essai à l'ONERA dans des conditions de basses températures et de basses pressions. La deuxième partie de cette thèse traite du développement d'un oscillateur paramétrique optique (OPO) nécessaire pour accorder en longueur d'onde dans l'infrarouge un laser impulsionnel picoseconde ou femtoseconde à haute cadence et forte puissance moyenne. Après avoir présenté la cavité de l'OPO ainsi que ses performances, nous détaillerons la capacité de cet OPO à générer des impulsions femtoseconde comprimées à partir d'impulsions pompe présentant un étirement temporel
This two-part thesis focuses on the development of nano and picosecond laser sources and their applications. The first part presents the study, and the realization of a nanosecond laser amplifier chain for the ignition of turboshaft engines. After the repport of the performances and the evolution of this amplifier chain will be presented the results of the tests carried out on a combustion chamber on a test bench at ONERA under low temperatures and low pressures conditions. The second part of this thesis deals with the development of an optical parametric oscillator (OPO) in order to tune in the infrared the wavelength of a pulsed picosecond or femtosecond laser at high cadency and high average power. After presenting the OPO cavity and its performance, we will detail the ability of this OPO to generate compressed femtosecond pulses from pump chirped pulses

This thesis proposes and demonstrates experimentally two novel linear-cavity tunable fibre lasers employing an erbium-doped fibre (EDF) in conjunction with an Opto- VLSI processor and a MEMS-based device for wavelength selection. The Opto-VLSI processor and the MEMS-based device along with an optical collimator, a Bragg grating plate and an optical lens, enable the realisation of an optical filter for continuous tuning of wavelengths over the amplified spontaneous emission (ASE) range of the EDF. We also propose the use of a section of un-pumped EDF as a saturable absorber (SA), which suppresses noise spikes caused by the high optical pumping power. Experimental results show that by optimising a length of the SA a single wavelength, high power laser signal can be achieved. In addition, we experimentally demonstrate that the performance of the proposed linear-cavity tunable fibre lasers is better than that of ring-cavity tunable laser counterparts. Specifically, we show that linear-cavity based tunable fibre lasers can achieve higher output power, a larger side mode rejection ratio (SMRR) and narrower laser linewidth than ring-cavity tunable fibre lasers.

Malgré le grand intérêt suscité par l’intégration de composants opto-électro-mécaniques (MOEMS) dans des systèmes optiques peu d’expérimentations concernant leur capacité à produire des impulsions optiques brèves sont développées. C’est donc dans cette direction que nous avons orienté nos travaux. Ce manuscrit dresse tout d’abord l’état de l’art sur les composants MOEMS puis présente les divers modes de fonctionnement des systèmes lasers impulsionnels. Le développement des MOEMS est exposé à travers les étapes de conception, d’optimisation du procédé de fabrication et de caractérisation. Nous démontrons ensuite le déclenchement actif de lasers à fibre basés sur l’intégration active de MOEMS. Nous présentons la réalisation d’un système laser multilongueur d’onde qui exploite l’achromaticité des micromiroirs pour la génération de radiations accordables dans le spectre visible. Enfin, nous étudions le développement de filtres réjecteurs de bande multipôles accordables
In spite of the large interest provoked by the integration of Micro-Opto-Electro-Mechanical-System (MOEMS) in optic systems, not enough experimentation concerning their capacity to produce short optic impulsions is developed. It is therefore in this direction that we orientated our jobs. First, this manuscript raises the state of art on MOEMS micro-mirrors and then introduces various kinds of pulsed laser systems regimes. The development of MOEMS is displayed across stages of conception, optimization of technology and characterization. We demonstrate a simple technique to produce active Q-switching in various types of fiber amplifiers by active integration MOEMS. We present the realization of a multiwavelength laser system which exploits the achromaticity of micro-mirrors for the generation of tunable radiations in the visible spectre. Finally, we study the development of tunable multipole reject band filters

Ce mémoire de thèse est consacré à l'étude d'une liaison tout-optique longue de 10 km dédiée à l'extension d'un observatoire câblé de fond de mer existant afin d'atteindre de nouvelles zones d'exploration. Les travaux de recherche qui y sont rapportés démontrent la faisabilité de cette liaison tout-optique entre un instrument déporté et une station terrestre avec une seule fibre optique longue de 10 km, qui transmet simultanément la puissance, nécessaire à l'alimentation de l'instrument (quelques centaines de milliwatts), et des données bidirectionnelles en temps réel.Le contexte de cette thèse est présenté au travers d'un état de l'art sur les observatoires câblés et sur la puissance sur fibre. Le choix de la fibre unique et la présence de fortes puissances optiques complexifient la mise en oeuvre de cette extension tout-optique, et sont à l'origine de l'apparition d'interactions entre l'énergie optique dédiée à l'alimentation (@1480 nm) et les données échangées (@1550 nm). Tout au long de ce document, les choix technologiques retenus sont argumentés et les effets optiques non linéaires tels que les diffusions Raman, Brillouin, Rayleigh, l'Émission Spontanée Amplifiée (ASE) sont décrits, modélisés et analysés expérimentalement. L'extension tout-optique proposée a été caractérisée à la fois en régimes statique et dynamique par des mesures du bilan de liaison, du rapport signal à bruit (SNR) et du taux d'erreur binaire (BER). Les résultats obtenus montrent la possibilité de fournir 160 mW électrique à l'instrument déporté en utilisant une source optique continue de 33 dBm sans dégrader excessivement les données bidirectionnelles transmises simultanément (BER<10-7).

Cette thèse concerne le développement de futurs appareils, systèmes et réseaux prenant en charge l’internet haute vitesse, sans fil 5éme g´enération (5G). La demande de débit très élevé nécessite une bande passante suffisante, et ainsi la bande de fréquence millimetrique (mm-wave) a beaucoup d’intérêt. Un certain nombre de technologies devront converger, coexister et interagir, et surtout, coopérer, si cette vision doit être efficace et rentable. Le concept principal de cette de 5G est l’intégration de réseaux de fibre optique et Les réseaux radio grâce à la technologie Radio-sur-Fibre (RoF) aux fréquences d’onde millimetriques, pour fournir des services à large bande passante et permettre des réseaux évolutifs et gérables sans structure d’interface très complexe et multiples protocoles superposés.Dans cette thèse, les systèmes de communication RoF à ondes millimetriques sont théoriquement étudiés et démontrés expérimentalement pour étudier les altérations du système. Le travail présenté dans cette thèse est axé sur le bruit optique représenté par le bruit de phase et d’intensité induit par la source optique et la dispersion chromatique introduite par la fibre optique. Le bruit optique est analysé et mesuré pour différentes techniques de génération optique. Deux dispositifs différents de conversion, un mélangeur et un détecteur d’enveloppe sont, appliqués pour le traitement du signal et pour décorréler la phase et le bruit d’intensité. Nous souhaitons souligner que cette étude et le modèle peuvent s’appliquer à tout type de système de génération optique hétérodyne et à toute gamme de fréquences. La corrélation entre les modes optiques en peigne à fréquence optique est examinée pour montrer l’impact de la dispersion chromatique. Cette thèse présente la distribution d’énergie des ondes millimetriques et son influence sur la portée des fibres et la façon dont l’effet de dispersion chromatique sur le réseau RoF depend des paramètres de dispersion. Ensuite, cette thèse démontre comment la décorrélation de la phase optique induite par la dispersion chromatique entraîne un bruit de partition de modes dans les réseaux de communication RoF à ondes millimétriques.Lors de la transmission de certains types de données sur le système, les résultats démontrent l’impact du bruit optique et de la dispersion chromatique sur le qualité du signal. Les résultats de simulation sont présentés et sont en très bon accord avec les résultats expérimentaux. La grandeur du vecteur d’erreur evaluée par en processus en ligne montre l’impact des altèrations du système sur les performances du système. Le débit de données et l’évolution du système présentée sont en conformité avec les normes de communication comme à ondes millimétriques
This thesis is for the development of future devices, systems and networks supporting the 5th Generation (5G) high-speed wireless internet. The demand for very high bit rate requires a sufficient large bandwidth, and therefore Millimeter-Wave (mm-wave) frequency band has a lot of interest. Several number of technologies will need to converge, co-exist and interoperate, and most importantly, cooperate, if this vision is to be efficiently and cost-effectively realized. The main concept within this next 5G is the integration of optical fiber networks and radio networks through Radio-over-Fiber (RoF) technology at mm-wave frequencies, to provide high-bandwidth front/backhaul services and enable scalable and manageable networks without a highly complex interface structure and multiple overlaid protocols.In this thesis, the mm-wave RoF communication systems are theoretically studied and experimentally demonstrated to investigate the system impairments. The work presented in this thesis is focused on optical noise represented by phase and intensity noise induced by optical source and chromatic dispersion introduced by optical fiber. The optical noise is analyzed and measured for different optical generation techniques. Two different down-conversion stages, mixer and envelope detector, are applied for signal processing and to decorrelate phase and intensity noise. We would like to highlight that this study and the model can be applicable toany kind of optical heterodyne generation system and any frequency range. The correlation among optical modes in optical frequency comb is examined to show the impact of chromatic dispersion. This thesis also exhibits the mm-wave power distribution over fiber span and how the chromatic dispersion effect on the RoF network is modified by varying dispersion parameters. Then, this thesis demonstrates how the optical phase decorrelation induced by chromatic dispersion results in mode partition noise at mm-wave RoF communication networks.When transmitting some types of data over the system, the results demonstrate the impact of optical noise and chromatic dispersion on the signal quality. The simulation results are presented and are in very good agreement with experimental results. The error vector magnitudethrough online process shows the impact of the system impairments on the system performance. The data rate and system evolution are compliance with communication standards at mm-wave

L'objectif de cette thèse est le développement de deux architectures d'oscillateurs optoélectroniques (OEO) afin de générer des signaux microondes très stables pour des applications radar. Les nouvelles génération de radar et de systèmes de guerre électronique requièrent le développement de nouvelles sources de signaux microondes très stables. La première architecture réalisée consiste à stabiliser le signal d'un laser bifréquence avec une boucle à verrouillage de fréquence optique. L'étude théorique et expérimentale du système a permis d'améliorer significativement la pureté spectrale du signal délivré par le laser. Implémenté avec une fibre optique de 100 m de long, l'oscillateur présente un bruit de phase de -105 dBc/Hz à 10 Hz de la porteuse avec une accordabilité de 2,5 à 5,5 GHz par pas de 2 MHz. Ces résultats correspondent aux limites techniques fixées par les composants hyperfréquences utilisés pour la boucle de stabilisation. L'implémentation de la boucle avec deux retards optiques en parallèles ou avec un anneau de fibre résonant comme retard optique est également étudiée. La seconde architecture développée est un oscillateur optoélectroniques couplé (COEO). Celle-ci, similaire à celle d'un laser à verrouillage de modes régénératif, résulte de l'imbrication d'une cavité laser à modes bloqués et d'une cavité optoélectronique résonante. Le développement du laser autour d'un amplificateur optique à semiconducteur (SOA) à semelle permet de tirer parti d'une puissance de saturation élevée et du faible bruit inhérent à ces composants. Nous mesurons avec ce dispositif une densité spectrale de puissance de bruit de phase de -135 dBc/Hz à 10 Hz de la porteuse à 10 GHz
The objectives of this thesis is the developement of two optoelectronic oscillator architectures dedicated to the generation of low noise microwave signals for radar applications. The first oscillator is based on the stabilization of the beatnote of a widely tunable dual-frequency laser with an optical fiber delay line. A fine analysis of the stabilization loop implemented with a 100 m long optical fiber allowed us to reach the technical limit fixed by the loop microwave amplifiers. The oscillator is tunable from 2. 5 to 5. 5 GHz by 2 MHz steps and present a phase noise power spectral density of -105 dBc/Hz at 10 kHz offset from the carrier (performance independent of the carrier frequency). The use of two optical fibers in a double delay lines architecture and of a fiber ring resonator as a delay line are also investigated. The second architecture developed is a coupled optoelectronic oscillator (COEO). The architecture, similar to a regenerative mode-locked laser, is realized by coupling a resonant laser cavity to a resonant optoelectronic loop. The developpement of this oscillator is based on a new architecture of SOA : an asymmetrical cladding semiconductor optical amplifier. This component offers better saturation power and lower intrinsic noise than the classical design. The COEO operates around 10 GHz. A phase noise power spectral density of -135 dBc/Hz is measured at 10 kHz offset from the carrier

The demand for optical power splitters is growing globally, due to the rapid deployment of fibre-to-the-premises, optical metropolitan area network (MAN), and active optical cables for TV/Video signal transport. Optical splitters play an important role in passive optical network (PON) technology by enabling several hundred users to share one optical line terminal. However, current PONs, which use fixed optical power splitters, have limited reconfigurability particularly in adding/dropping users to/from an optical network unit. An adaptive optical power splitter (OPS) can dynamically reallocate the opticalpower in the entire network according to the real-time distribution of users and services, thus providing numerous advantages such as improve an optical network efficiency, scalability, and reliability. An adaptive OPS is also important for realizing self-healing ring-to-ring optical MAN, thus offering automatic communication recovery when line break occurs. In addition, future optical line protection systems will require adaptive optical splitters to switch optical signals from faulty lines to active power lines, avoid the use of optical attenuators and/or amplifiers, and achieve real time line monitoring. An adaptive OPS can also be incorporated in tunable optical dispersion compensators, optical attenuator and optical gain equalizer, and reconfigurable optical switches. This thesis proposes and demonstrates the principle of a novel Opto-VLSI-based adaptive optical splitter/combiner for next generation dynamic optical telecommunication networks. The proposed splitter structure enables an input optical power to be split adaptively into a larger number of output fibre ports, through optimized phase holograms driving the Opto-VLSI processor. The new adaptive optical splitter has additional advantages including lossless operation, adequate inter-port crosstalk, compressed hardware and simple user interface. This thesis demonstrates, in particular, the concept of an adaptive optical power splitter employing an Opto-VLSI processor and a 4-f imaging system experimentally in three stages as follow: (i) a 1×2 adaptive optical power splitter based on an Opto-VLSI processor, a fibre collimator array and 4-f imaging systems (single lens), (ii) a 1×4 adaptive optical power splitter based on an Opto-VLSI processor, a fibre array and 4-f imaging systems (single lens), and (iii) a 1×N lossless adaptive optical power splitter structure integrating an Opto-VLSI processor, optical amplifiers, a fibre array, and an array of 4-f imaging systems (lens array). The thesis also demonstrates the concept of an adaptive optical signal combiner which enables multiple signals to be combined with user-defined weight profiles into a single fibre port. Experimental results demonstrate that an input optical signal can arbitrarily be split into N signals and coupled into optical fibre ports by uploading optimized multicasting phase holograms onto the Opto-VLSI processor. They also demonstrate that N input optical signals can be dynamically combined with arbitrary weights into a single optical fibre port. Excellent agreement between theoretical and experimental results is demonstrated. The total insertion loss of the optical power splitter is only 5 dB. Results also show that the optical amplifiers can compensate for the insertion and splitting losses, thus enabling lossless splitter operation. A crosstalk level around -25 dB and a wavelength spectral range exceeding 40 nm is experimentally realized. In addition, a novel broadband adaptive RF power splitter/combiner based on Opto-VLSI processor is proposed and experimentally demonstrated. By uploading optimized multicasting phase holograms onto the software-driven Opto-VLSI processor, the input RF signal is dynamically split and directed to different output ports, with userdefined splitting ratios. Also, multiple input RF signals can be dynamically combined with arbitrary user-defined weights. As a proof-of-concept demonstration, two input RF signals are dynamically combined with different user-defined weight profiles. We also propose and demonstrate a photonic microwave filter based on the use of an Opto-VLSI-based adaptive optical combiner. The experimental results demonstrate that the developed Opto-VLSI-based adaptive optical combiner can dynamically route multiple input optical signals to a single output, with user-defined weight profiles, thus realising a tunable microwave filter. Overall this Opto-VLSI-based adaptive optical power splitter should allow as many as 32 output ports to be supported while achieving high splitting resolution and dynamic range. This will greatly enhance the efficiency of optical communication networks.

博士
國立清華大學
光電工程研究所
97
利用週期性鋰酸鈮晶體建構一連續式、單波長光參數共振腔，進而產生一從可見光到中紅外光之可調雷射光源，為一個相當有效率的方法，其中的優點包含了高的轉換效率與極窄的輸出頻譜寬度。近來，由於連續式光纖雷射的迅速發展，其高輸出功率與近乎理想高斯分佈的空間特性，已經廣泛的被利用在光參數共振腔之幫浦光源上，這本論文發表了世界第一個，利用寬頻光纖雷射作為中紅外光參數共振腔的幫浦光源，並產生單頻之中紅外光源；同時，並利用光纖雷射幫浦一光參數共振腔，搭配腔內與腔外的波長轉換器，產生紅、藍、綠全彩雷射。 在此論文一開始，為了展現週期性鋰酸鈮晶體的多用途特性，我們先驗證了單一週期性鋰酸鈮晶體，可以同時當作波長轉換器與雷射Ｑ值調變器，接著，我們利用一寬頻(1 nm)的1064 nm光纖幫浦雷射與一摻鎂週期性鋰酸鈮晶體為增益介質，得到了一連續式、單頻的中紅外雷射，在幫浦功率為25瓦與輸出波長為1.58與3.2 um時，我們得到輸出功率分別為5.3 與1.2瓦； 此外，藉由量測，超過瓦級之3.2 um光源為單頻輸出，同時其頻譜線寬為5 MHz。由於週期性鋰酸鈮晶體對於共振之中紅外波長有輕微的吸收行為，我們觀察到熱吸收引起的雙穩態與熱波導效應，當共振腔內功率達到熱波導閾質３０瓦時，熱波導可以使光參數增益增加兩倍，由於幫浦雷射頻寬過寬，我們同時在幫浦雷射頻譜中觀察到燒洞現象。 波長可調的可見光雷射，可以藉由在紅外單波長光參數共振腔內串接兩級合頻產生器，將近紅外之幫浦雷射做頻率上轉換的方式來產生，我們將一寬頻的1064 nm光纖幫浦雷射光源轉換到可見光區域，並得到瓦級、連續式、紅、綠、藍全彩雷射，此近紅外單波長光參數共振腔之共振波長為1.56 um，並在共振腔內串接兩級合頻產生器得到紅、藍光，同時再利用一外部的倍頻器，將剩餘之幫浦雷射轉換到綠光，在25瓦幫浦功率時，我們得到4瓦的紅光(633 nm)、0.48瓦的綠光(532 nm) 、0.057瓦的藍光(450 nm)。

碩士
國立臺北科技大學
光電工程系研究所
104
The fast development of optical communications has raised the requirements for high bandwidth and high-speed data access not only for single-mode fiber (SMF)-based optical fiber backbone but also for radio-frequency (RF)/optical wireless-based feeder networks. Through the large bandwidth of optical fiber and the flexibility of RF/optical wireless transmission, fiber-wireless and fiber-invisible laser light communication (IVLLC) convergences have progressed to meet multiple gigabit demands. Fiber-wireless and fiber-IVLLC convergences can utilize the advantages of both optical and wireless technologies; that is, they can use the naturally enormous bandwidth of optical fiber and the unused bandwidth in microwave (MW) and millimeter-wave (MMW) bands. Fiber-wireless and fiber-IVLLC convergences can cover service areas with faster speed and lower cost by virtue of fiber long-haul and RF/optical wireless short-range technologies. In this thesis, fiber-wireless and fiber-IVLLC convergences based on MZM-OEO-based BLS to transmit downstream 10 Gbps/30 GHz MW, 15 Gbps/50 GHz MMW, 20 Gbps/60 GHz MMW, and 25 Gbps/100 GHz MMW data signals, as well as upstream 25 Gbps baseband (BB) data stream, are proposed and experimentally demonstrated. Through a comprehensive investigation of such bidirectional fiber-wireless and fiber-IVLLC convergences, Bit error rate (BER) performs efficiently in a 40-km SMF and a 10-m RF/25-m optical/100-m optical wireless transport scenarios. Such fiber-wireless and fiber-IVLLC convergences for MW/MMW/BB signal transmission will be an attractive approach for providing broadband-integrated services, including Internet, telecommunication, and data communication services.

Tese de mestrado integrado, Engenharia Física, Universidade de Lisboa, Faculdade de Ciências, 2021
In recent years, increasing efforts of developing novel micro and nano technologies have been dedicated to improve human health. These advances in the field of nanotechnology have facilitated the development of miniaturized microfluidic lab-on-a-chip (LOC) devices, which are frequently described as miniature versions of their macro-scale counterparts. Microfluidic LOC devices present great benefits in terms of small sample volumes and fast analysis times. From an optical point of view, these devices still suffer a drastic reduction in the optical pathlength compared to macroscale experiments. Obviously the reduced optical pathlength complicates or reduces the effectiveness of the application of various optical techniques in lab-on-a-chip systems. Meanwhile these devices are gaining a broader acceptance in clinical medicine for disease diagnosis. This thesis describes the recent work performed in the field of optofluidics with the application of optical sensing systems for microfluidic devices. Optofluidics is a combination of optics/photonics and microfluidics field. In optofluidic devices the micro-photonic components are integrated on microfluidic devices, which are able to hold the fluids at the microlitre scale. Optofluidic devices are used to perform interactions between light and fluids at micro scale level for applications in physics, chemistry and biology. These chip-scale devices could be easily integrated into a LOC system that is a compact platform and does not require free-space optics to perform laser-based spectroscopy, such as absorption spectroscopy. Absorption spectroscopy (AS) is a powerful technique for studies of species (atoms and molecules) and detection of unknown concentrations. The spectroscopic analysis is not only applied in physics and chemistry but also in biology and medicine [1]. Although a large number of molecular species can successfully be detected with established AS techniques, there are some applications that require higher sensitivity, selectivity and accuracy, yet robust and compact instrumentation. In this work, a LOC device was developed based on the optofluidics concept. The relevance of integration of micro-optical components in an “on-chip” approach is compared with the “off-chip” approach which was coupled with macro-scale optical infrastructure. The design and characterization of miniaturized optofluidic devices for sensing based on integrating collimating optical fibers with custom microfluidic chips is presented. The usage of graded-index (GRIN) fiber tips or GIF tips is to develop a compact device which does not require free space optics and the collection efficiency of GRIN fiber tips is significantly higher compared to standard single-mode fiber. The absorption spectroscopy on-chip is performed with both GIF tips and SMF configurations. To compare the performance of both fibres, the beam divergence and the insertion losses were measured. The reduction in both beam divergence and insertion losses for the GIF configuration compared with SMF were found to be 4-fold, for a 10 mm channel. Absorption spectroscopy was demonstrated on chip for the measurement of red colour dye (Ponceau 4R) and the detection of thiocyanate (SCN) which is an indicator of oral health and a detoxification product of cancer treatments. The thiocyanate concentrations were detected in water and also in a complex biofluid i.e. artificial human saliva. The proposed optofluidic setup allows for absorption spectroscopy measurements to be performed with only 200 µL of solution which is an order of magnitude smaller than for standard cuvettes but provides comparable sensitivity. To assess the performance of the miniaturized device, the absorption measurements are also compared with a standard cuvette of the same pathlength (~10 mm). A quantitative comparison of both devices demonstrates the consistency of linearity of absorbance against the concentration of analyte, accordingly to the Beer-Lambert law. The demonstrated approach has the potential to be used for chemical and biochemical analysis of DNA, proteins or saliva where the use of small volumes is critical. In order to perform spectroscopic analysis of human body proteins, a new sensing device was developed using a compacted chip with micropillar arrays called “Pillar Cuvette (PC)”. The PCs are fabricated at ANFF-SA (Australian National Fabrication Facility - South Australia Node). The design and fabrication process of PCs is briefly presented in this thesis. The CLIC3-HIS tag protein (human body protein) and BSA protein (Bovine protein) spectroscopic analysis were performed in UV range of spectrum. We developed a new approach to optical manipulation of excitation fibre and collection fiber setup. The proposed design and setup are presented in which optical fibers and the PC are integrated directly on a compact platform that doesn’t require alignment. It is an integrated pre-aligned device which is wholly portable.
Nos últimos anos, os esforços crescentes de desenvolvimento das novas tecnologias têm-se dedicado a melhorar a saúde humana. Esses avanços no campo da nanotecnologia facilitaram o desenvolvimento de dispositivos microfluídicos, designados lab-on-a-chip (LOC), que são frequentemente descritos como versões em miniatura de seus equivalentes em macro escala. A área dos microfluídicos trata dos fluidos em escala micrométrica para fins de controlo de fluxo ou deteção das espécies químicas. Os dispositivos microfluídicos apresentam grandes vantagens, incluindo consumo mínimo de volumes de amostra, tempos de análise rápidos e custo de fabricação reduzido [2]. Com o avanço nas tecnologias de fabricação, as áreas de ótica e da fotónica também se adaptaram para desenvolver componentes óticos na micro e nano escala. A pesquisa na escala micrométrica deu origem a outro tópico chamado opto-fluídos. A área de opto-fluídos é muito recente, surgiu apenas no início de ano 2000 e a pesquisa neste tópico está crescendo exponencialmente de um ano para o outro [3]. A área de opto-fluídos estuda a interação entre fluído e luz, aproveitando a tecnologia existente nas áreas de microfluídicos da ótica. Os dispositivos opto-fluídos são geralmente baseados na integração de tecnologias óticas/fotónicas no dispositivo microfluídico. Do ponto de vista ótico, os dispositivos opto-fluídos sofrem uma redução drástica no comprimento do caminho ótico, em comparação com os instrumentos em macro escala. Obviamente, o comprimento do caminho ótico reduzido complica ou traz problemas na utilização de técnicas de deteção e isso, por sua vez, reduz a eficácia das técnicas óticas em sistemas LOC. Enquanto isso, esses dispositivos estão a ganhar aceitação crescente no campo da medicina clínica para o diagnóstico de várias doenças. A presente tese descreve o trabalho recente realizado na área de opto-fluídos, utilizando um sistema de sensores óticos num dispositivo microfluídico. Os dispositivos opto-fluídicos são usados para realizar interações entre luz e fluídos em nível de microescala para aplicações em física, química e biologia. Os componentes óticos ao nível de escala de um micro-chip podem ser facilmente integrados em um sistema LOC que também é uma plataforma compacta. Deste modo, os sistemas opto-fluídos não requerem ótica de espaço livre para realizar espectroscopia baseada em laser, como a espectroscopia de absorção. A espectroscopia de absorção é uma técnica poderosa para estudos de espécies (átomos e moléculas) e deteção de concentrações desconhecidas. Embora um grande número de espécies moleculares possa ser detetado com sucesso através das várias técnicas estabelecidas de espectroscopia, existem algumas aplicações que requerem maior sensibilidade, precisão e instrumentação mais robusta e compacta. Neste trabalho pretendeu-se desenvolver um dispositivo LOC com base no conceito de opto-fluídos. A espectroscopia de absorção foi demonstrada no dispositivo compacto e miniaturizado (LOC) desenvolvido usando fibras que têm pontas de índice graduado (GRIN) que também são conhecidas por pontas GIF. Essas fibras permitem desenvolver um lab-on-a-chip altamente eficaz que é compacto, conectada por fibra e que não requer ótica de espaço livre para criar o caminho ótico. A espectroscopia de absorção no chip é realizada com duas configurações, ou seja, pontas GIF e SMF. Para comparar o desempenho de ambas as fibras, a divergência do feixe e as perdas de inserção foram medidas. A eficiência de coleção do feixe na ponta de fibra GRIN (125 µm) é significativamente maior em comparação com a fibra de modo único - SMF (125 µm). As pontas GIF têm o feixe colimado na saída da fibra que é transmitida longitudinalmente através de um microcanal e que é coletada por uma fibra multi-modo na outra extremidade do microcanal. Desta forma, fabricamos um dispositivo opto-fluídico que permite melhorias significativas no aumento do comprimento de interação, para espectroscopia de absorção de passagem única, usando pontas de fibra de índice graduado (GIF). A relevância da integração de componentes micro-óticos na abordagem on-chip é comparada com a abordagem off- chip, que foi acoplada à infraestrutura ótica em macro escala. A configuração opto-fluídica proposta permite que as medições de espectroscopia de absorção sejam realizadas com apenas 200 µL de solução, que é uma ordem de magnitude menor do que as efetuadas com uma cuvete padrão (3.5 mL), mas que fornece sensibilidade comparável. Para avaliar o desempenho do dispositivo miniaturizado, as medições de absorção também são comparadas com uma cuvete padrão do mesmo caminho ótico (~10 mm). A espectroscopia de absorção foi demonstrada em 3 configurações (cuvete padrão; dispositivo opto-fluídico com fibra SMF; dispositivo opto-fluídico com fibra GIF) para a medição do corante vermelho (Ponceau 4R). Para demonstrar ainda mais o uso do dispositivo opto-fluídico, mostramos que esse pode ser usado para a deteção de analitos biologicamente relevantes, como o thiocyanate (SCN). O SCN foi escolhido porque é um produto usado na desintoxicação de fármacos utilizados no tratamento do cancro e é um indicador de saúde bucal, incluindo a exposição ao fumo passivo que pode aumentar significativamente as concentrações de SCN para níveis potencialmente capazes de afetar a glândula tireoide. Numa comparação quantitativa, o dispositivo demonstrou a consistência da linearidade da absorbância em relação à concentração do analito, de acordo com a lei de Beer-Lambert Também exploramos a configuração opto fluídica com a ponta GIF para deteção de SCN em uma matriz de uma amostra mais complicada (que não é apenas água) a saliva humana artificial. Reforçando assim, o estudo do potencial deste dispositivo para diagnóstico de amostras complexas. A abordagem demonstrada mostrou ter potencial para ser usada para análises químicas e bioquímicas de ADN, proteínas ou saliva onde o uso de pequenos volumes é crítico. De modo a fazer comparação entre duas fibras, foram efetuados estudos de feixe de divergência ao longo de microcanal e as perdas de inserção entre a fibra de excitação (GIF) e a fibra de coleção (MMF). Foi obtida uma redução 4 vezes inferior na divergência do feixe e nas perdas de inserção para a configuração GIF em comparação com SMF, para um canal de 10 mm de comprimento. O trabalho foi complementado com a análise espectroscópica das proteínas do corpo humano. Para tal, foi utilizado um chip compactado com matrizes de micropilares denominado Pillar Cuvette ou PC. Os PC foram fabricados na ANFF- SA (Australian National Fabrication Facility - South Australia Node). O processo de desenho e fabricação do PC é brevemente apresentado neste trabalho. A análise espectroscópica da proteína CLIC3-HIS tag (proteína do corpo humano) e da proteína BSA (proteína bovina) foi realizada na faixa de espectro do ultravioleta (UV). Utilizando os métodos prévios não foi possível determinar o pico de absorvância esperado a λ=280 nm. Face a este resultado, foi desenvolvido um novo dispositivo opto fluídico que tem alta viabilidade de integração na plataforma lab-on-a-chip. Neste novo dispositivo as pontas GIF são configuradas num PC. Na nova configuração desenvolvida, o feixe é transmitido através da secção transversal do PC, permitindo aumentar o comprimento do caminho ótico mantendo 2 µL - 3 µL de volume de amostra. Para futuro trabalho, o desenho de uma plataforma foi desenvolvido para integração compacta dos PC e das ambas as fibras. Esta nova plataforma está em processo de fabricação e será testado nas futuras experiências. Um bom resultado nos testes permitirá alargar o universo de utilização destes dispositivos em análises químicas e bioquímicas com volume de amostra e tempo de análise reduzido. Deste modo, a crescente disponibilidade de ferramentas e técnicas na indústria de nanotecnologia vai fornecer um caminho para trazer essas inovações do laboratório para a vida cotidiana.