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Saab, Kassem. "Optique adaptative pour les télécommunications optiques". Thesis, Paris Sciences et Lettres (ComUE), 2017. http://www.theses.fr/2017PSLEO016/document.
Pełny tekst źródłaFree space optical communications are able to allow rates of several tens of gigabits/s. In order to process these flows and benefit from the techniques developed in the context of fiber optics, it is desirable to inject the received beam into a single mode fiber. In this case, adaptive optics is proposed to limit the injection losses induced by the degradation of the beam quality caused by the atmospheric turbulence.In this thesis, we consider a link between a satellite and a ground receiving station.For high elevations when amplitude perturbations can be averaged by increasing the size of the pupil and the correction of the phase is sufficient by conventional adaptive optics (AO), this work deals with the experimental implementation of the coupling optimization between a conventional AO and a single mode fiber, by correcting the non common path aberrations between the measurement path of the wave front and the injection path of the corrected signal. The accomplished work in this context is summarized by the following tasks: definition of an automatic injection optimization method by controlling a single deformable mirror for the parallel correction of fast phase disturbance and quasi-static differential aberrations; numerical study of the implementation of the proposed method defined end-to-end simulations ; implementation of the method in the laboratory on the BOA bench, modeling the atmospheric turbulence by rotating phase screens, and validation of the injection optimization in closed loop ; application of the method on the ODISSEE bench at the OCA and closing of the loop on a laser signal emitted by the Japanese satellite SOCRATE.Besides, the link must be operational for a maximum duration. Indeed, the system must operate even when the satellite is low on the horizon and, therefore, when the crossed portion of atmosphere is thick. In these particular conditions, the disturbances induced by the air index fluctuations are stronger than for astronomical observations, so that, the simultaneous correction of the phase and the amplitude is essential to reach the desired injection ratio (> 50 %). Based on this analysis, the second part of this thesis focuses on the study of the experimental implementation of an innovative approach of a phase and amplitude correction based on using an integrated Mach-Zehnder. The work done in this part consists in the following points : elaboration of correction principle by a Mach-Zehnder and proposition of a generalized device with N channels ; theoretical analysis of the superposition by the proposed device ; development of a control algorithm based on the architecture proposed in integrated optics ; numerical validation of operation by end-to-end simulations ; design of the prototype for the experimental validation of the concept in the laboratory
N'Gadi, Lucien Yao. "Optimisation d'un réseau de communication par fibre optique". Mémoire, Université de Sherbrooke, 2008. http://savoirs.usherbrooke.ca/handle/11143/4797.
Pełny tekst źródłaNanni, Jacopo. "High performance, low cost and low consumption Radio over fiber Systems for diversified communications applications". Thesis, Paris Est, 2018. http://www.theses.fr/2018PESC1162/document.
Pełny tekst źródłaThis dissertation aims to analyze the possibility of improving in terms of cost and consumption the future Radio-over-Fiber (RoF) systems in different telecommunication scenarios, such as current and next generation of cellular networks and in other applications such as Radio Astronomy. The RoF system studied is hence composed of a Vertical Cavity Surface Emitting Laser (VCSEL) operating at 850 nm, standard single mode fiber (SSMF) and SiGe Heterojunction Phototransistor (HPT), adopting the technique called Intensity Modulation{Direct Detection which is nowadays the cheapest and simplest architecture for RoF. This dissertation describes in detail the multimode propagation within the SSMF (designed to operate only at 1310 nm and 1550 nm) which is present at 850 nm. Through a developed mathematical model, the two-modes propagation is described and the main phenomena involved are analyzed. In particular, the model focus on intermodal dispersion and modal noise which are considered the two main contributions of performance detrimental. The model developed is able to identify the main parameters which contribute to enhance the detrimental effects produced by intermodal dispersion and modal noise both in frequency and time domain. Starting from the model, possible techniques to improve the performances are then proposed. In particular, a pre-filtering technique is realized in order to avoid the excitation of the second order mode, allowing a quasi-single-modepropagation within the SSMF. The technique is theoretically and experimentally validated either for single radio frequency sinusoidal transmission either for bandpass signal transmission centered in radio frequency band. In particular it is demonstrated experimentally the possibility of increasing the modulationbandwidth of the RoF system, reducing at the same time the fluctuations of power and gain. Furthermore, the technique is validated in a real LTE transmission system, making the RoF technology proposed able to transmit 256-QAM LTE signal of 20 MHz bandwidth, confirming the possibility of using this technology to decrease the overall cost and consumption of the network. Further work hasbeen done on the mathematical model. In particular the two modes propagation is exploited reversely in order to characterize the chirp parameter of the VCSEL employed. Finally, the problem of coupling between fiber and opto-electronic devices is also discussed and investigated, in order to enhance theperformances while keeping low the cost. The possibility of utilizing a collective and passive ploymerbased structure for coupling the optical fiber with small area photodetectors and VCSEL is presented, showing important improvements on coupling efficiency and tolerance to misalignment
Benyahya, Kaoutar. "Mode group division multiplexing for short reach optical communications". Thesis, Rennes 1, 2019. http://www.theses.fr/2019REN1S117.
Pełny tekst źródłaThe ever-growing demand of data traffic will be fuelled by revolutionary technologies such as virtual reality (VR), augmented reality (AR) and Internet of things (IoT). Therefore, optical networks should support the requirements of these services in terms of high capacity, low latency and high reliability. In fact, large scale capacity is a critical need for fiber optic communication systems deployed in local area networks as well as in datacenters. For both applications, systems relying on intensity modulation and direct detection (IMDD) are highly demanded due to their low cost and compatibility with short range applications. In this thesis, we address the need of increasing the data rates for short reach optical communication systems based on mode group division multiplexing and direct detection schemes. Firstly, we focus on increasing the capacity of already deployed standard multimode fibers in local area networks and intra-datacenters communication where the distance is shorter than 5 km. Secondly, we extend our solution to longer reach applications such as inter-datacenter interconnects. In both cases, optical link architectures, including transmitters, receivers and the optical fibers are analysed. Moreover, modulation formats adapted to IMDD systems such as single carrier 4-PAM and multicarrier DMT are compared in the context of space division multiplexing transmission. In this work we demonstrated the achievable benefit of mode group multiplexing combined with IMDD schemes. First, 5 Tb/s has been achieved over 2.2 km of conventional multimode fiber (OM2). Secondly, transmission record at the corresponding time of its realization of 14.5 Tb/s over OM2 fiber is demonstrated. Finally, 200 Gb/s over 20 km of FMF has been achieved which extend the benefit of mode group multiplexing to longer reach applications compared to LAN and intra-datacenter where the maximum distance is limited to 5 km
Seck, Aida. "Contribution à l’optimisation des systèmes de transmission optiques cohérents (Nx100 Gbit/s) utilisant le multiplexage en polarisation par des formats de modulation en phase et une conception de ligne limitant l’impact des effets non-linéaires". Thesis, Evry, Institut national des télécommunications, 2014. http://www.theses.fr/2014TELE0008/document.
Pełny tekst źródłaThe ever-increasing demand of capacity in very high bit rate coherent optical transmission systems has paved the way towards the investigation of several techniques such as the use of ultra-low loss fibers, Erbium doped fiber amplifiers, polarization and wavelength division multiplexing (WDM), coherent detection, multi-level modulation formats, spatial division multiplexing, etc. However, there are questions concerning polarization division multiplexing and a development towards some advanced modulation formats including phase modulation and polarization division multiplexing. In this thesis, in order to increase the capacity-by-distance product of future optical coherent systems using wavelength and polarization division multiplexing, we first study spectral shaping of the transmitted signals to increase the information spectral density. For this purpose, we have numerically investigated the multi-channel transmission performance of Polarization Switched Quadrature Phase Shift Keying (PSQPSK) and we have compared it to the performance of Polarization-Division-Multiplexed QPSK (PDM-QPSK), using Root Raised Cosine (RRC) spectral shaping, in the context of a flexible channel grid. In addition we have presented the advantage of PS-QPSK against PDM-QPSK as a function of the system parameters, while we have also discussed the benefit of a RRC spectral shaping against a tight filtering at the transmitter side with a 2nd order super-Gaussian-shaped filter. Furthermore, we have focused on nonlinear effects that limit the transmission distance by degrading the transmitted symbols during propagation. Analyzing and reducing the impact of nonlinear effects is essential when using technologies that increase the information spectral density such as polarization division multiplexing which causes new nonlinear effects due to additional interactions between symbols during the propagation through the fiber. Therefore a reduction of the impact of nonlinear effects is necessary for the development of future systems with higher bit rates of 400 Gbit/s and 1 Tbit/s per channel. We have established in this thesis, design rules to reduce the impact of nonlinear effects in the optical WDM transmission systems at 100 Gbit/s per channel that use polarization multiplexing
Ye, Xiaoyan. "Applications of Artificial Intelligence to Control and Analyze the Performance of Fiber-Optic Transmission Systems". Electronic Thesis or Diss., Institut polytechnique de Paris, 2023. http://www.theses.fr/2023IPPAT048.
Pełny tekst źródłaThe surging demands for internet traffic have necessitated continuous expansion in opticalfiber communication systems capacity, cornerstone of global communication networks. This thesisdelves into innovative solutions addressing the challenges posed by ultra-wideband (UWB) amplificationand precise noise estimation in optical transmission systems. Optical fiber communication systems haveundergone significant evolution to meet escalating capacity requirements. Progressing from optical amplifiersand coherent detection to advanced modulationformat and digital signal processing (DSP) algorithms. To meet the need for higher traffic demands in opticalnetworks, integrating UWB schemes and implementing low-margin network designs have becomeprimordial. This work explores fundamental aspects of UWB amplification. Accurate prediction of Ramangain profiles and optimal pump configurations design is paramount, yet conventional methods prove computationallyintensive. Here, Machine Learning (ML) emerges as a powerful tool, simplifying complexityand enhancing accuracy in these scenarios. Additionally, the thesis addresses the challenge of designinglow-margin systems by developing a reliable Quality of Transmission (QoT) tool. Optical fiber transmissionsystems contend with diverse impairments such as fiber attenuation, ASE noise, laser phase noise, nonlinearinterference (NLI), etc. While linear impairments can be effectively mitigated and characterized, traditionalmethods may falter in estimating some major nonlinear impairments, posing challenges in accuracyand complexity. Consequently, this work delves into data-driven approaches, including ML frameworks,to provide effective estimation of Kerr nonlinear impairments and electronically enhanced phase noise(EEPN) In summary, this thesis leverages ML and data-driven methods to enhance the performance ofoptical transmission systems. These advancements are poised to shape the future of optical communicationsystems, facilitating higher capacities and more reliable transmissions in our rapidly evolving digitalenvironment
Lefebvre, Kim. "Technique de réutilisation de longueur d'onde optique dans des applications RoF basée sur les RSOA pour des communications bidirectionnelles OOK et OFDM". Master's thesis, Université Laval, 2019. http://hdl.handle.net/20.500.11794/37718.
Pełny tekst źródłaKhayatzadeh, Ramin. "Convergence des technologies optique et radio pour la génération dédiée aux communications aux fréquences supérieures à 60 GHz". Thesis, Université Grenoble Alpes (ComUE), 2015. http://www.theses.fr/2015GREAT074/document.
Pełny tekst źródłaThis Ph.D. investigates the radio over fiber communication systems at mm-wave frequencies higher than 60 GHz. The thesis elaborates on three crucial issues in these systems including:phase noise measurement of unstable optically generated mm-wave signals, elimination ofphase noise impact on performance of radio over fiber systems using non-coherent down conversion technique, and studying the amplitude noise impacts on performance of system based on these detectors. In the first part of this work, a new digital phase noise measurement technique is presented which is able to extract the phase noise of any unstable mm-waveoptically generated signal. This technique is able to measure the phase noise for a widerange of offset frequencies from close-in phase noise to far noise floor by adapting frequency resolution of measurement and without considering small angle approximation. In the second part, we present a radio over fiber system at mm-wave frequency based on non-coherent electrical frequency down conversion stage using an envelope detector which is robust against phase and frequency fluctuations of the optically generated carrier signal. Finally, a the oreticaland experimental study of amplitude noise impact on performance of radio over fiber systemsbased on non-coherent receivers is presented. In this study, a simulation technique based ontheory is developed which is able to determine, among different optical and electrical noise, the one which has the dominant effect on EVM results. This simulation technique is based onobserving the EVM evolution versus received optical power
Arnould, Aymeric. "Ultra-wideband and high symbol rate transmission systems for next-generation optical fiber communications". Electronic Thesis or Diss., Institut polytechnique de Paris, 2021. http://www.theses.fr/2021IPPAS006.
Pełny tekst źródłaOptical fiber transmissions have enabled the development of the high capacity and resilient networks that form the backbone of the modern-day global telecommunication system. Whereas low-loss fibers and erbium doped fiber amplifiers (EDFA) allow wavelength division multiplexing (WDM), coherent detection enables advanced modulation and coding schemes, and digital signal processing (DSP) is used to compensate for physical propagation effects. In this thesis, we address possible solutions for the next generation coherent WDM systems. Semiconductor optical amplifiers (SOA) are used to provide ultra-wideband (UWB) seamless amplification over more than 100 nm, a promising way to scale the throughput compared to conventional systems using EDFA with bandwidth less than 40 nm. We show that custom UWB SOA can enable WDM transmission in high power regime, and we demonstrate UWB WDM experimental transmissions leveraging the SOA bandwidth. In particular, the design of specific amplification schemes is presented, and the nonlinear impairments arising from UWB spectrum transmission are characterized. Furthermore, the industry fosters the development of high symbol rate transceivers to provide cost-efficient optical WDM systems with reduced number of transceivers per fiber link. This work studies the capacity and limitations of next-generation coherent transceivers, operating at symbol-rates up to 100 GBd. We investigate the impact of equalization enhanced phase noise, which is a potentially dominant impairment at high symbol rates. We demonstrate high symbol rate transmissions, from regional distances to ultra-long-haul subsea distances in laboratory conditions, as well as in a field trial over a live commercial traffic network. Using probabilistic constellation shaping and powerful forward error correcting codes, we show the flexibility provided by high symbol rate transceivers to address the different transmission cases that constitute the core of the Internet communication network
Yi, Lilin. "Ralentissement de la lumière par effets non-linéaires dans les fibres optiques pour les systèmes de communications à haut débit". Paris, ENST, 2007. http://www.theses.fr/2007ENST0037.
Pełny tekst źródłaSlow light, referring to slowing down the propagation velocity of the light through engineering the material dispersion or waveguide dispersion of the medium, is a promising technology for optical buffering and packet synchronization in future all-optical communication networks. Recently, slow light in fibers are rapidly developing for their compatibility with fiber-optic communication systems, where the fiber nonlinearities such as stimulated Brillouin scattering (SBS), stimulated Raman scattering (SBS) and parametric process are used to shape the material dispersion of the fiber so as to realize the slow light based on the well-known Kramers-Kronig relationship. What’s more, for being compatible with the present 10-Gb/s optical communication systems, the system performances of 10-Gb/s signals delayed in the fiber nonlinearities based slow light should be thoroughly evaluated. In this thesis, we utilize the narrow band parametric process and broadband SBS in fiber to realize the tunable delay of 10-Gb/s signals. We evaluate the performances of the slow-light delay lines by measuring the maximal delay time, the fractional delay and the signal quality such as eye opening and bit-error-rate (BER) of the delay signal, and optimize the signal quality by minimizing the slow-light induced distortions
Saibi, Fadi. "Traitement du signal pour les communications optiques à haute efficacité spectrale". Phd thesis, Télécom ParisTech, 2005. http://pastel.archives-ouvertes.fr/pastel-00001045.
Pełny tekst źródłaFracasso, Bruno. "Des interconnexions holographiques à l'aiguillage dynamique pour les réseaux de communications optiques". Habilitation à diriger des recherches, Université de Bretagne Sud, 2010. http://tel.archives-ouvertes.fr/tel-00691577.
Pełny tekst źródłaAbu-Romoh, Mohanad. "Equalization in Optical Fiber Communication Using Model-based Neural Networks". Electronic Thesis or Diss., Institut polytechnique de Paris, 2023. http://www.theses.fr/2023IPPAT037.
Pełny tekst źródłaMeeting the increasing demand for highspeed data transmission requires effective solutions for mitigating nonlinearity in optical communication systems. Traditional methods like Digital Backpropagation (DBP) face significant computational challenges,rendering them impractical for real-world systems. Neural network models have emerged as a promising approach to address this issue. Two primary approaches exist for designing neural networks: model-agnostic and model-based methods. Modelagnostictechniques offer flexibility in terms of size and hyperparameters and can be placed at various positions in the receiver’s Digital Signal Processing (DSP) chain. However, they demand substantial size and extensive training data in order to operate effectively.In contrast, model-based approaches employ neuralnetworks guided by the physical model of signal propagation. These approaches tend to be more compactbut require careful initialization for proper generalization. One prominent model-based technique isLearned Digital Backpropagation (LDBP), which optimizes DBP parameters using neural networks. LDBPoffers the promise of improved performance or reduced complexity compared to DBP. This study primarilyfocuses on LDBP, introducing simplifications through ”parameter sharing” to reduce trainable parameters.Additionally, we propose repurposing the legacy Dispersion-Managed (DM) systems, by incorporatinghigher-order modulation formats such as 16- QAM and 64-QAM, to enhance data rates within these systems. A comprehensive analysis of the performance and complexity demonstrates that the proposed algorithms outperform linear equalization andDBP in various transmission systems
Audo, Frédéric. "Opto-alimentation et transmission de données par fibre optique pour les observatoires de fond de mer". Phd thesis, Université de Bretagne occidentale - Brest, 2012. http://tel.archives-ouvertes.fr/tel-00782502.
Pełny tekst źródłaNguyen, Anh Tuan. "Utilisation de l'optique fibrée pour la manipulation et la génération d'états quantiques: pile ou face quantique et paires de photons". Doctoral thesis, Universite Libre de Bruxelles, 2008. http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/210446.
Pełny tekst źródłaapporte une nouvelle description du monde qui nous entoure et en
particulier de ce qu'on appelle le monde de l'infiniment
petit. Cette nouvelle théorie permet une description adéquate
notamment de l'effet photoélectrique, des niveaux énergétiques des
atomes, des réactions nucléaires, Elle apporte également une
réponse à de nombreuses problématiques telles que la catastrophe
ultraviolette. Néanmoins aussi séduisante que soit cette théorie,
les prédictions pour le moins contre-intuitives qu'elle apporte,
amène rapidement la controverse. Par exemple, en 1935, A.
Einstein, B. Podolski et N. Rosen en arrivent à mettre en doute la
physique quantique à cause d'une particularité que l'on y
rencontre, à savoir l'enchevêtrement. Il s'en
suit le célèbre débat avec N. Bohr et l'école de Copenhagen. Parmi
les autres aspects propres au monde quantique on peut encore citer
la superposition des états, le postulat de la mesure, le principe
d'incertitude d'Heisenberg, la dualité onde-corpuscule, le
théorème de non clonage, Toutes ces spécificités font de la
physique quantique un monde passionnant dans lequel, à l'instar du
pays des merveilles d'Alice, l'intuition est souvent dépassée.
Cette thèse est le fruit de quatre années de travail au cours
desquelles nous avons tenté d'observer et d'étudier certains des
effets intrigants que nous propose la physique quantique. Plus
précisément nous avons utilisé des états particuliers de la
lumière afin d'explorer une partie de ce qu'on appelle
l'optique quantique.
Dans un premier temps nous nous sommes intéressés aux possibilités
offertes par l'utilisation d'états cohérents de la lumière. En
utilisant ces états particuliers nous nous sommes penchés sur
l'étude ainsi que sur la réalisation expérimentale d'une tâche qui
se révèle impossible classiquement sans hypothèse computationelle.
Cette tâche consiste à réaliser un pile ou face entre deux joueurs
éloignés l'un de l'autre, par exemple deux joueurs communiquant
par téléphone. En effet, classiquement, un des deux joueurs pourra
toujours tricher de manière à avoir 100% de chance de gagner le
pile ou face.
Au contraire, si on utilise les ressources offertes par la
communication quantique, il est possible de construire des
protocoles ne permettant plus à aucun des deux joueurs de tricher
parfaitement et ce, sans aucune hypothèse supplémentaire. Même si
aucun protocole quantique ne peut empêcher totalement toute
tricherie, leur démonstration constitue une preuve de principe
quant aux possibilités offertes par la physique quantique dans la
réalisation de tâches classiquement impossibles.
Lors de notre étude du problème, nous avons développé un protocole
de pile ou face quantique et étudié ses performances. Nous avons
montré que les tentatives de tricherie des deux joueurs avaient
une probabilité de succès limitée à 99,7%<100% (biais inférieur
à 0,497). L'originalité de cette étude se situe dans le fait que
les imperfections expérimentales (efficacité des détecteurs,
pertes de transmission, visibilité réduite, ) furent prises en
compte, ce qui à notre connaissance n'avait jamais été réalisé. En
outre nous avons réalisé une implémentation en optique fibrée de
notre protocole et démontré la réalisation d'un pile ou face
unique au cours duquel aucun des deux joueurs ne pouvait
influencer parfaitement le résultat, ce qui à notre connaissance
n'avait également jamais été démontré. L'emploi d'états cohérents
de la lumière fortement atténués nous a donc permis de concevoir
un protocole de pile ou face quantique et de réaliser une
démonstration expérimentale en optique fibrée, d'une tâche
impossible à réaliser classiquement.
Après avoir travaillé avec des états cohérents fortement atténués,
nous nous sommes intéressés à un autre état quantique de la
lumière, à savoir les paires de photons. Ces états constituent non
seulement une ressource essentielle pour sonder les effets
quantiques de la lumière mais également une ressource
incontournable pour l'information et la communication quantique.
Nous nous sommes donc attelés à la réalisation d'une source
produisant ces paires de photons.
Les premières sources de paires
de photons furent basées sur l'utilisation de cristaux dans
lesquels il existe une interaction non linéaire entre la lumière
et le matériau du cristal. Malheureusement le désavantage majeur
de ces sources est la difficulté à collecter les paires de photons
générées. Nous avons donc étudié la possibilité de générer des
paires de photons directement dans une fibre optique, la
collection des paires y étant réalisée de facto.
La première solution que nous avons envisagée consiste à utiliser
la non-linéarité du troisième ordre de la silice composant les
fibres optiques. Plus précisément le phénomène utilisé est appelé
l'instabilité de modulation. Ce phénomène permet de détruire deux
photons de pompe afin de générer une paire de photons vérifiant
les conservations de l'énergie et de l'impulsion. En outre nous
avons choisi d'utiliser une fibre optique microstructurée. Ces
fibres permettent en effet un plus grand confinement de la lumière
que les fibres standards. Il en résulte une interaction non
linéaire plus importante, permettant ainsi de générer des paires
de photons de manière plus efficace. La fibre utilisée est en
outre biréfringente, ce qui permet d'avoir accès à deux types
particuliers d'instabilité de modulation: l'instabilité scalaire
et l'instabilité vectorielle.
Dans un premier temps, nous avons observé le processus
d'instabilité de modulation dans un régime classique. Les
paramètres particuliers de notre fibre microstructurée - forte
dispersion anormale et biréfringence modérée
- nous ont permis d'observer un régime
d'instabilité dans lequel l'instabilité de modulation vectorielle
se produit à des fréquences proches de la fréquence de pompe
($Omegasim 1$THz). Il en résulte que les bandes de gain liées à
l'instabilité de modulation vectorielle sont très proches des
bandes de gain liées à l'instabilité de modulation scalaire. Nous
avons observé que dans ce régime particulier, les densités
d'énergie générées par instabilité de modulation vectorielle sont
supérieures à celles générées par instabilité de modulation
scalaire. A notre connaissance, il s'agit de la première
observation expérimentale permettant de mettre en évidence un gain
vectoriel supérieur au gain scalaire.
La génération de paires de photons grâce à ce processus nécessite
de diminuer la puissance de pompe envoyée dans la fibre.
Malheureusement nous avons mesuré que dans ce régime de faible
puissance (régime quantique), la qualité des paires de photons
générées était fortement dégradée par la présence de photons
parasites générés par diffusion Raman spontanée. Nous avons estimé
que lorsque la puissance de pompe est abaissée suffisamment pour
générer en moyenne 0,1~photons dans la bande de gain d'instabilité
de modulation vectorielle ($sim$1543 nm), environ 75% des
photons détectés auront été générés par diffusion Raman spontanée.
Afin de mettre en oeuvre des expériences d'optique quantique
utilisant des paires de photons, des solutions doivent donc être
appliquées à notre source afin de réduire le nombre de photons
générés par diffusion Raman spontanée. Parmi ces solutions nous
pouvons citer la discrimination en polarisation des photons
générés ainsi que le refroidissement de la fibre grâce à de
l'azote liquide. Ces solutions permettraient de réduire le nombre
de photons Raman anti-Stokes d'un facteur 18 et le nombre de
photons Raman Stokes d'un facteur 4. Malheureusement la tenue de
la fibre microstructurée à de très basses températures reste
incertaine et l'implémentation de ces solutions rendrait la source
difficilement utilisable.
Notre première tentative pour générer des paires de photons dans
une fibre optique nous a montré que les paires de photons générées
grâce à un processus d'interaction non linéaire du troisième ordre
étaient polluées par des photons générés par diffusion Raman
spontanée. Une source de paires de photons efficace ne pouvait
donc pas être obtenue sans l'aide de solutions technologiques
assez lourdes à mettre en oeuvre.
Nous avons donc investigué une deuxième solution afin de réaliser
une source produisant des paires de photons dans une fibre
optique. Puisque les non-linéarités du troisième ordre semblent
être peu adaptées pour la génération de paires de photons, nous
sommes revenus à une non-linéarité du second ordre. Dans ces
processus c'est un photon de pompe qui est détruit afin de générer
une paire de photons, tout en respectant les conservations de
l'énergie et de l'impulsion. Malheureusement les fibres optiques
ne permettent pas l'apparition de non-linéarités du second ordre
et ce, à cause de la centrosymétrie macroscopique du verre de
silice qui compose ces fibres.
Afin d'induire une non-linéarité du second ordre dans une fibre
optique nous avons travaillé en collaboration avec l'équipe du
Prof. P. G. Kazansky de l'université de Southampton. En utilisant
les techniques de poling thermique et d'effacement par
illumination UV, ils réalisèrent une fibre optique twin-hole
périodiquement polée dans laquelle les non-linéarités du second
ordre furent possibles.
Grâce à cette fibre nous avons réalisé une source de paires de
photons combinant les avantages des effets non linéaires du second
ordre, i.e. la puissance de pompe nécessaire est moindre
que dans le cas d'une non-linéarité du troisième ordre, la
diffusion Raman spontanée n'influence aucunement les paires de
photons générées, et les avantages de la fibre optique,
i.e. la collection des paires de photons y est réalisée
de facto, le mode spatial transverse des paires de photons
est bien défini. La mesure du pic de coïncidences de notre source
fournit un rapport entre le sommet du pic et le niveau des
coïncidences accidentelles de 7,5. Une efficacité conversion
$P_s/P_p=1,2,10^{-11}$ fut obtenue en utilisant 43~mW de
puissance de pompe. En outre les paires de photons générées
possèdent une longueur d'onde de 1556~nm se trouvant ainsi dans la
bande C des télécommunications optiques (1530-1565~nm). Elles sont
donc bien adaptées à une éventuelle application en communication
quantique, dans les réseaux de fibres optiques actuellement
utilisés pour les télécommunications optiques. Enfin nous avons
utilisé ces paires de photons afin de réaliser l'expérience de
Hong-Ou-Mandel permettant de mettre en évidence un effet propre à
la physique quantique, à savoir le photon bunching. Une visibilité
nette de 40% fut obtenue pour le Mandel dip dans une
configuration où la visibilité maximale vaut 50%. En outre cette
expérience nous a permis de développer une expertise dans la
réalisation d'interféromètres fibrés, stabilisés et contrôlés en
température.
La source de paires de photons que nous avons réalisée constitue
une démonstration de principe quant à la faisabilité d'une telle
source. A l'époque de ce travail, la fibre dont nous disposions
était l'une des premières fibres twin-hole périodiquement polées.
Aujourd'hui de nombreux paramètres de la fibre ont été améliorés
et permettent la réalisation d'une source de paires de photons
tout à fait compétitive avec les autres sources existantes. Ainsi
l'équipe du Prof. Kazansky est capable de réaliser des fibres
périodiquement polées de 20 cm de long possédant une efficacité de
conversion normalisée de seconde harmonique de
$eta_{SH}=8;10^{-2}$\\%/W. Si l'on suppose toujours une puissance
de pompe de 43 mW, cela mène à une efficacité de conversion de
$1,0;10^{-9}$ pour le processus de fluorescence paramétrique,
soit une amélioration de deux ordres de grandeurs par rapport à
notre démonstration. La réalisation d'une source de paires de
photons dans une fibre optique périodiquement polée qui serait non
seulement utilisable dans des expériences de physique fondamentale
mais également dans des applications en communication quantique,
est donc tout à fait envisageable dans un futur proche.
Pour résumer, nous avons, au cours de cette thèse, réalisé, dans
un premier temps, la tâche classiquement impossible qui consiste à
jouer à pile ou face à distance. Ensuite dans l'optique de générer
des paires de photons, nous avons étudié le processus
d'instabilité de modulation dans une fibre microstructurée. Nous
avons ainsi observé un régime particulier dans lequel
l'instabilité de modulation vectorielle possède un gain supérieur
à celui de l'instabilité de modulation scalaire. Enfin toujours en
quête d'une source de paires de photons, nous avons réalisé une
source produisant des paires de photons par fluorescence
paramétrique dégénérée au sein d'une fibre optique twin-hole
périodiquement polée. Les trois principaux sujets abordés au cours
de cette thèse ont donc en commun l'utilisation de l'optique
fibrée pour la manipulation ou la génération d'états quantiques de
la lumière. Il en a résulté l'obtention de trois résultats
originaux qui nous ont ainsi permis d'explorer une partie du monde
intrigant et fascinant de l'optique quantique.
/
Quantum physics was introduced early in the 20th century. It
brings a whole new description of our world, mostly at the
microscopic level. Since then, this new theory has allowed one to
explain and describe lots of physical features like the
photoelectric effect, the energy levels of atoms, nuclear
reactions, It also brought an answer to lots of remaining
unanswered questions like the so-called ultraviolet catastrophe.
Though, as attractive as this new theory was at that time, some of
its counter-intuitive predictions quickly gave rise to
controversy. For instance, in 1935, due to one quantum physics
feature called entanglement, A. Einstein, B. Podolski and N. Rosen
asked the question: "Can quantum-mechanical description of
physical reality be considered complete?". This led to
the famous debate with N. Bohr and his Copenhagen interpretation.
Amongst other particular features of quantum physics one can cite:
the superposition principle, the wave function collapse, the
Heisenberg uncertainty principle, the wave-particle duality, the
no-cloning theorem, As in Alice in wonderland, all those
features actually make quantum physics a fascinating world where
intuition is most of the time useless.
In this thesis we tried to observe and study some of the
intriguing features of quantum physics. More precisely we tried to
use specific light states to explore part of what is called
quantum optics.
First we studied the use of coherent states of light to perform
tasks you can not perform using classical physics. For instance in
1984, Ch. Bennett and G. Brassard proposed the first quantum
cryptography protocol which has an absolute security
while classical protocol security still relies on some
computational assumptions (the assumption is that today
computers computational power is not sufficient to threaten the
security of classical protocols. Though this means that classical
protocols are not intrinsically secure). Since then quantum
physics has been proven useful to perform lots of classically
impossible tasks like bit commitment, quantum computation, random
number generation, In this work we were interested in the
problem of coin tossing by telephone introduced by M. Blum
in 1981. In this problem two untrustful and distant
players try to perform a coin flip. Classically one can show that,
if no computational assumptions are made, one of the players can
always force the outcome of the coin flip.
On the opposite if one uses quantum communication resources, a
protocol in which none of the players can cheat perfectly can be
built, i.e. none of the players have 100\\% chance of
winning the protocol even by using the best possible cheating
strategy. Moreover this is possible without any other assumption
than the validity of the laws of physics. Though a quantum
protocol for coin tossing can not completely prevent from cheating, the demonstration of such a protocol would
be a proof of principle of the potential of quantum communication
to implement classically impossible tasks.
In our work, we have developed a quantum coin tossing protocol and
studied its performances. We have shown that the success cheating
probability of the players is bounded by 99,7%<100%, which is
better than what is achieved in any classical protocol. One of the
originalities of our work is that, for the first time to our
knowledge, experimental imperfections (detectors efficiency,
losses, limited interference visibility, ) have been taken into
account in the theoretical analysis. Moreover, using coherent
states of light, we have demonstrated a fiber optic experimental
implementation of our protocol and performed a single coin flip
where none of the two players could perfectly influence the
outcome. This is to our knowledge the first experimental
demonstration of single quantum coin tossing.
After coherent states of light, we wanted to work with a more
complex quantum state: photon pairs. Not only those states are
useful for fundamental physics tests but they also are an
important resource for quantum communication. For those reasons
our first objective was to build a source that would generate
those photon pairs.
First photon pairs sources were based on bulk nonlinear crystals.
Unfortunately the main drawback of those sources is the low
collection efficiency of the generated photon pairs. That's why we
investigated the possibility of generating the photon pairs
directly in a waveguiding structure where they would be readily
collected.
The first solution that we envisaged was to use the natural third
order nonlinearity of silica fibers. More precisely the phenomenon
we wanted to used is called modulation instability. In this
process, two pump photons are destroyed and a photon pair is
created with energy and momentum conservations. Moreover we
decided to use this process in a photonic crystal fiber. The high
confinement of light in this kind of fiber allows a higher
nonlinearity and thus a more efficient generation of photon pairs.
Finally the fiber we used was birefringent which enables both
vectorial and scalar modulation instability to occur.
As a first experiment, we decided to observe modulation
instability in a classical regime where a lot of photons are
created. The specific parameters of our photonic crystal fiber -
high anomalous dispersion and moderate birefringence - allowed us
to observe a regime where the vectorial instability gain band has
a similar detuning from the pump as the scalar instability gain
band. In this regime we also observed an enhancement of the
vectorial gain above the scalar gain which has been confirmed
theoretically. To our knowledge this was the first experimental
observation of this particular regime of instability.
To generate photon pairs with this instability process we need to
lower down the pump power. Unfortunately we measured that, when
pump power was sufficiently lowered to generate ~0,1 photon
pairs per pump pulse sent in the fiber, about 75% of generated
photons were created by spontaneous Raman scattering and not
modulation instability. In order to build an efficient photon pair
s secteurs financiers et, en particulier, au rôle de la religion musulmane. Nous montrons que, en moyenne, la finance islamique favorise le développement du secteur bancaire dans les pays musulmans. Plusieurs pays ont en effet réussi à développer un nouveau secteur bancaire compatible avec la Shariah, sans porter ombrage au secteur bancaire non islamique avec lequel il co-existe. Notre analyse empirique est fondée sur une base de données nouvelle et originale. Celle-ci a pour intérêt de fournir des indicateurs de taille et de performance des banques islamiques de dépôt dans le monde, pour la période 2000-2005.
Dans le deuxième essai, nous explorons les rendements inconditionnels obtenus sur les marchés boursiers, en particulier les marchés émergents d'actions. Notre analyse d'un large panel de 53 marchés émergents "Majeurs" et "Frontières" confirme les résultats traditionnellement observés dans la littérature. Ainsi, pour l'essentiel, les deux types de marchés sont volatils et émaillés d'événements extrêmes. De plus, les rendements des marchés émergents sont faiblements corrélés avec ceux du reste du monde, même si ces corrélations ont augmenté au cours des derniers décennies. Malgré d'importantes différences en terme de taille et de liquidité, les rendements sur marchés "Frontières" sont qualitativement similaires à ceux des marchés "Majeurs", à l'exception des corrélations. Ces dernières sont en effet actuellement plus faibles dans les marchés "Frontières", qui continuent dès lors à offrir d'importants bénéfices de diversification aux investisseurs internationaux.
Dans le dernier essai, nous examinons la relation entre les transferts d'argent des migrants et la croissance économique. Nous confirmons l'idée que les transferts de fonds des migrants sont importants pour les pays en voie de développement. Mais surtout, nous démontrons, de manière théorique et empirique, qu'il est crucial de faciliter dans ces pays l'accès aux comptes de dépôt bancaires, afin de transformer une plus grande part des transferts des migrants en investissements productifs. Ceci est d'autant plus vrai quand l'accès aux autres sources de capitaux internationaux est coûteux.
on pairs well defined). A coincidence
measurement was performed resulting in a coincidence peak with a
7,5 ratio between the peak and the accidental coincidences level.
A conversion efficiency $P_s/P_p=1,2,10^{-11}$ was obtained using
43 mW of pump power. Moreover photon pairs were generated around
1556~nm in the optical communications C-band, which makes them
suitable for quantum communication applications using installed
fiber optic networks. Finally using the generated photon pairs we
performed the Hong-Ou-Mandel experiment highlighting the bosonic
nature of photons. We obtained a Mandel dip with a net visibility
of 40% in a configuration where the maximum visibility is 50%.
The photon pair source that we realized is a proof of principle of
the high potential of poled fibers in quantum applications. Indeed
today, Prof. P. G. Kazansky's team is able to make a 20 cm poled
fiber with a nonlinearity $eta_{SH}=8;10^{-2}$\\%/W. If we still
suppose 43~mW of pump power, this leads to a $1,0;10^{-9}$
conversion efficiency for parametric fluorescence, improving our
result by two orders of magnitude. The realization of an efficient
photon pair source based on parametric fluorescence in
periodically poled twin-hole fiber suitable for quantum
applications is thus absolutely possible in a very near future.
Doctorat en Sciences de l'ingénieur
info:eu-repo/semantics/nonPublished
Liu, Jingtian. "Shaping Strategies to Embrace Nonlinear Effects in Optical Fiber Communications". Electronic Thesis or Diss., Institut polytechnique de Paris, 2024. http://www.theses.fr/2024IPPAT007.
Pełny tekst źródłaThe main impediment in long-distance communications is nonlinear interference (NLI), stemming from nonlinear effects in optical fibers. While Digital signal processing algorithms offer partial mitigation, the inherent nonlinear nature of the fiber, coupled with predominant dispersion effects, continues to challenge the increase of transmission throughputs. Addressing nonlinearity at the information source through signal modulation technology is at the heart of our research. Traditional modulation schemes, as spectral efficiency climbs, such as QAM, become increasingly susceptible to NLI while their Mean Squared Euclidean Distance (MSED) diminishes. While multi-dimensional (MD) modulation yields improved linear and partial nonlinear gains, it has not yet demonstrated tangible benefits. On the other hand, the emergence of probabilistic constellation shaping (PCS), preferred for its enhanced linear gain and compatibility with conventional modulation hardware and software, introduces additional NLI. Consequently, the design of nonlinear-tolerant PCS is emerging as a pivotal research direction. Our thesis begins with a novel MD modulation for uniformly distributed signals. Then, we propose a novel approach combining MD with PCS to examine performance variations. Delving into PCS, we investigate the enumerative sphere shaping distribution matcher (DM), initially from an MD stance, and design a DM optimized for nonlinear tolerance over shorter distances. Subsequently, we introduce a new NLI measurement technique, accounting for dispersion effects. Integrating this with the sequence selection framework of PCS, we achieve successful long-distance transmission with notable nonlinear gains
Jenneve, Philippe. "Analyse Expérimentale des Distorsions Non-Linéaires pour la Construction d’un Estimateur de Performances des Réseaux Optiques Cohérents". Thesis, Université Paris-Saclay (ComUE), 2016. http://www.theses.fr/2016SACLO014.
Pełny tekst źródłaNowadays, high-speed fiber-optic communication networks are the basis of information technology and the subject of intense research. Innovation enables transponders to be flexible and versatile, but fiber optical networks are still configured manually and especially almost never tuned during the life of the network. One of the blocking points toward reconfigurable and automated optical networks is the need of performance prediction for any link of the network in an accurate and fast way. However, the prediction is made even more complex by the diversity of deployed optical fiber types and propagation regimes.During my work, I addressed experimentally the signal distortions coming from nonlinear Kerr effects accumulated on hundreds of kilometers of optical fibers. Based on specific and controlled experiments, I have measured and highlighted the properties of the nonlinear distortions. These analyses allowed me to design a performance model estimator that can be applied to heterogeneous optical links with various optical fiber types and propagation regimes.The flexibility of transponders associated with a performance estimator will optimize and tune the channels dynamically depending on the load and the topology of the network, as well as compute the protection and restoration links
De, Valicourt Guilhem. "Conception, fabrication, et évaluation de modulateurs déportés pour les réseaux d'accès et radio sur fibre". Phd thesis, Télécom ParisTech, 2011. http://pastel.archives-ouvertes.fr/pastel-00677397.
Pełny tekst źródłaBenzazaa, Mostafa. "Etude d'architectures de systèmes de transmission de signaux ULB RF et millimétriques avec lien optique : application à la Radio-sur-Fibre". Paris 6, 2011. http://www.theses.fr/2011PA066218.
Pełny tekst źródłaSUDARYANTO. "Reseaux hybrides de communication optique, numeriques et analogiques, en fibre et en espace libre. Materiels, logiciels et interfacage pour la conception et l'exploitation". Université Louis Pasteur (Strasbourg) (1971-2008), 1991. http://www.theses.fr/1991STR13187.
Pełny tekst źródłaSemenkoff, Mathilde. "Contribution à l'étude des amplificateurs optiques à fibre pour les systèmes de transmission multi-longueurs d'onde". Saint-Etienne, 1995. http://www.theses.fr/1995STET4003.
Pełny tekst źródłaShahkarami, Abtin. "Complexity reduction over bi-RNN-based Kerr nonlinearity equalization in dual-polarization fiber-optic communications via a CRNN-based approach". Electronic Thesis or Diss., Institut polytechnique de Paris, 2022. http://www.theses.fr/2022IPPAT034.
Pełny tekst źródłaThe impairments arising from the Kerr nonlinearity in optical fibers limit the achievable information rates in fiber-optic communication. Unlike linear effects, such as chromatic dispersion and polarization-mode dispersion, which can be compensated via relatively simple linear equalization at the receiver, the computational complexity of the conventional nonlinearity mitigation techniques, such as the digital backpropagation, can be substantial. Neural networks have recently attracted attention, in this context, for low-complexity nonlinearity mitigation in fiber-optic communications. This Ph.D. dissertation deals with investigating the recurrent neural networks to efficiently compensate for the nonlinear channel impairments in dual-polarization long-haul fiber-optic transmission. We present a hybrid convolutional recurrent neural network (CRNN) architecture, comprising a convolutional neural network (CNN) -based encoder followed by a recurrent layer working in tandem. The CNN-based encoder represents the shortterm channel memory arising from the chromatic dispersion efficiently, while transitioning the signal to a latent space with fewer relevant features. The subsequent recurrent layer is implemented in the form of a unidirectional vanilla RNN, responsible for capturing the long-range interactions neglected by the CNN encoder. We demonstrate that the proposed CRNN achieves the performance of the state-of-theart equalizers in optical fiber communication, with significantly lower computational complexity depending on the system model. Finally, the performance complexity trade-off is established for a number of models, including multi-layer fully-connected neural networks, CNNs, bidirectional recurrent neural networks, bidirectional long short-term memory (bi-LSTM), bidirectional gated recurrent units, convolutional bi-LSTM models, and the suggested hybrid model
Abouseif, Akram. "Emerging DSP techniques for multi-core fiber transmission systems". Electronic Thesis or Diss., Institut polytechnique de Paris, 2020. http://www.theses.fr/2020IPPAT013.
Pełny tekst źródłaOptical communication systems have seen several phases in the last decades. It is predictable that the optical systems as we know will reach the non-linear capacity limits. At the moment, the space is the last degree of freedom to be implemented in order to keep delivering the upcoming capacity demands for the next years. Therefore, intensive researches are conducted to explore all the aspects concerning the deployment of the space-division multiplexing (SDM) system. Several impairments impact the SDM systems as a result from the interaction of the spatial channels which degrades the system performance. In this thesis, we focus on the multi-core fibers (MCFs) as the most promising approach to be the first representative of the SDM system. We present different digital and optical solutions to mitigate the non-unitary effect known as the core dependent loss (CDL). The first part is dedicated to study the performance of the MCF transmission taking into account the propagating impairments that impact the MCF systems. We propose a channel model that helps to identify the MCFs system. The second part is devoted to optical technique to enhance the transmission performance with an optimal solution. After, we introduced digital techniques for further enhancement, the Zero Forcing pre-compensation and the space-time coding for further CDL mitigation. All the simulation results are validated analytically by deriving the error probability upper bounds
Slim, Joseph. "Optical signal processing for space division multiplexed systems". Thesis, Rennes 1, 2021. http://www.theses.fr/2021REN1S004.
Pełny tekst źródłaWhile the main advantage of optical communications is to enable transmission of ultra-high capacities by multiplexing dozens of wavelength channels operating at high bit rates, the processing of the data, for instance in view of its regeneration or routing, needs to be performed in the electrical domain, thus requiring optical-to-electrical-to-optical conversions. However, some processing functionalities could be performed more efficiently directly in the optical domain, which is known as all-optical signal processing. As new techniques exploiting the spatial dimension in multimode fibers have been proposed in order to further increase the transmitted capacity, a better understanding of nonlinear effects associated with multimode interactions is desirable. This thesis aimed to explore paths for all-optical signal processing in modedivision multiplexing. In particular, the target was to demonstrate how nonlinear effects in multimode fibers could be used to manipulate the properties of optical signals, either in a mode independent way, or mode dependent way. Two types of fibers were designed. The first one allows to perform some all-optical signal processing functionalities for all the modes of the fiber individually and simultaneously, by using the intramodal fourwave mixing nonlinear effect. The second fiber was designed in a way to perform all-optical signal processing between different modes of the fiber, using intermodal four-wave mixing
Amari, Abdelkerim. "Compensation des effets nonlinéaires pour les transmissions WDM longue distance à 400Gbps et au-delà". Electronic Thesis or Diss., Paris, ENST, 2016. http://www.theses.fr/2016ENST0031.
Pełny tekst źródłaOptical communication systems have evolved since their deployment to meet the growing demand for high-speed communications. Over the past decades, the global demand for communication capacity has increased exponentially and the most of the growth has occurred in the last few years when data started dominating network traffic. In order to meet the increase of traffic demands fueled by the growth of internet services, an increase of access network capacity and consequently metro and long-haul network capacities is required. Next generation of long-haul WDM transmission systems is expected to operate at 400Gbps or 1Tbps bit rate. Superchannel approaches, such as Nyquist WDM and multi-band OFDM, allow both high spectral efficiency and small guardband which makes them promising candidates to generate these high bit rates in combination with multi-level modulations formats. Such transmission systems are strongly disturbed by fiber nonlinear effects which increase with the data rate and the small guard band. Therefore, fiber nonlinearities compensation is required to get the desired performance in terms of transmission reach. DSP based approaches such as digital back propagation and third-order Volterra based nonlinear equalizer have been already proposed to deal with intra-channel or intra-band nonlinear effects. In the context of superchannel systems, we have proposed two new compensation techniques to deal with fiber nonlinear effects. The first one, called fifth-order inverse Volterra based nonlinear equalizer, compensate for intra-band nonlinear effects. The second approach, which is the interband/ subcarrier nonlinear interference canceler, is proposed to combat the nonlinear interference insuperchannel systems
Gatti, Sylvain. "Inscription laser UV pulsé sur nouveau matériau hybride pour codeurs optiques intégrés". Phd thesis, Montpellier 2, 2007. http://www.theses.fr/2007MON20238.
Pełny tekst źródłaLa technologie sol-gel a déjà démontré son potentiel. Un nouveau matériau sol-gel hybride à polymérisation cationique de type Epoxy a été développé dans le but de la simplification de la synthèse et de l'amélioration des performances en particulier l'adhérence.
Ce travail a pour objectif le développement d'un banc d'écriture laser UV dans une couche Epoxy et l'établissement du protocole de fabrication associé. Ce procédé de polymérisation locale est une alternative prometteuse aux techniques lithographiques par masque.
Ce nouveau banc utilise un laser pulsé travaillant à faible longueur d'onde pour une meilleure résolution et une meilleure polymérisation.
Ce travail a montré la faisabilité de circuits complexes de type multiplexeurs WDM avec un procédé d'inscription à faible coût. Nous avons réalisé les premiers prototypes de circuits dédiés à la sélection multiple de longueurs d'onde pour le (dé)codage du CDMA optique spectral.
Gatti, Sylvain. "Inscription laser UV pulsé sur nouveau matériau hybride pour codeurs optiques intégrés". Phd thesis, Université Montpellier II - Sciences et Techniques du Languedoc, 2007. http://tel.archives-ouvertes.fr/tel-00258256.
Pełny tekst źródłaLa technologie sol-gel a déjà démontré son potentiel. Un nouveau matériau sol-gel hybride à polymérisation cationique de type Epoxy a été développé dans le but de la simplification de la synthèse et de l'amélioration des performances en particulier l'adhérence.
Ce travail a pour objectif le développement d'un banc d'écriture laser UV dans une couche Epoxy et l'établissement du protocole de fabrication associé. Ce procédé de polymérisation locale est une alternative prometteuse aux techniques lithographiques par masque.
Ce nouveau banc utilise un laser pulsé travaillant à faible longueur d'onde pour une meilleure résolution et une meilleure polymérisation.
Ce travail a montré la faisabilité de circuits complexes de type multiplexeurs WDM avec un procédé d'inscription à faible coût. Nous avons réalisé les premiers prototypes de circuits dédiés à la sélection multiple de longueurs d'onde pour le (dé)codage du CDMA optique spectral.
Amari, Abdelkerim. "Compensation des effets nonlinéaires pour les transmissions WDM longue distance à 400Gbps et au-delà". Thesis, Paris, ENST, 2016. http://www.theses.fr/2016ENST0031/document.
Pełny tekst źródłaOptical communication systems have evolved since their deployment to meet the growing demand for high-speed communications. Over the past decades, the global demand for communication capacity has increased exponentially and the most of the growth has occurred in the last few years when data started dominating network traffic. In order to meet the increase of traffic demands fueled by the growth of internet services, an increase of access network capacity and consequently metro and long-haul network capacities is required. Next generation of long-haul WDM transmission systems is expected to operate at 400Gbps or 1Tbps bit rate. Superchannel approaches, such as Nyquist WDM and multi-band OFDM, allow both high spectral efficiency and small guardband which makes them promising candidates to generate these high bit rates in combination with multi-level modulations formats. Such transmission systems are strongly disturbed by fiber nonlinear effects which increase with the data rate and the small guard band. Therefore, fiber nonlinearities compensation is required to get the desired performance in terms of transmission reach. DSP based approaches such as digital back propagation and third-order Volterra based nonlinear equalizer have been already proposed to deal with intra-channel or intra-band nonlinear effects. In the context of superchannel systems, we have proposed two new compensation techniques to deal with fiber nonlinear effects. The first one, called fifth-order inverse Volterra based nonlinear equalizer, compensate for intra-band nonlinear effects. The second approach, which is the interband/ subcarrier nonlinear interference canceler, is proposed to combat the nonlinear interference insuperchannel systems
Lagrost, Alexandra. "Génération de peignes de longueurs d'ondes à haut débit pour les télécommunications optiques". Phd thesis, Université Rennes 1, 2010. http://tel.archives-ouvertes.fr/tel-00656651.
Pełny tekst źródłaGuillory, Joffray. "Radio over Fiber (RoF) for the future home area networks". Thesis, Paris Est, 2012. http://www.theses.fr/2012PEST1083/document.
Pełny tekst źródłaThe evolution of the Home Area Network (HAN) is lead by the proliferation of connected devices inside the home and the deployment of high broadband access network which now allows the delivery of services that can exceed 1Gbit/s. To ensure efficient in-house exchanges, the HAN has to move rapidly toward multi-Gigabit/s connections, in particular the wireless connectivity generally preferred by the customers. Current wireless systems have limited capacities, but new radio standards delivering data-rates up to 7Gbit/s are emerging. Nevertheless, as they address the unlicensed millimeter-wave band, from 57 to 66 GHz, their radio coverage is limited to a single room. Indeed, at such frequencies, the free-space losses are high and the waves do not cross the walls. This thesis proposes to solve this problem by means of the Radio over Fiber (RoF) technology. This consists in capturing the 60GHz radio signals emitted in one room, converting them into optical signals for transmission through optical fibers, and reemitting them in another room. Thus, several RoF transducers will be installed in the home and interconnected by a suitable optical infrastructure to create systems acting at the same time as repeaters and as distribution systems. From the viewpoint of the HAN market, such systems will be competitive only if they are low cost. As a consequence, this work focuses on direct modulation with direct detection (IM-DD) at Intermediate Frequency (IF). In other words, the 60GHz signal is down-converted at a lower frequency around 5GHz before the laser modulation and up-converted to 60GHz after the photodetection. Concerning the optical fiber, silica multimode fiber (MMF) is privileged as it allows the use of low cost and largely available optoelectronic devices working at 850nm.The thesis proposes different RoF architectures, from point-to-point interconnecting two rooms to multipoint-to-multipoint acting as logical buses. After an analog characterization of the optoelectronic components, the RoF link and the domestic cable, these architectures are designed, built and characterized step by step using OFDM modulation according to existing wireless 60GHz standards. Real-time transmissions between commercial devices have also been performed to validate these architectures. Moreover, advanced RoF infrastructures are proposed. First, the RoF systems can be easily improved if the access to their optical media is managed by the radio MAC layer. This approach is therefore studied showing its feasibility. Secondly, an optical system, seen by users as a premium product, has to support the legacy home services commonly used as well as the new ones that could emerge in the future. Thus, innovative multiservice and multiformat infrastructures conveying on a unique optical cable wired IP data, broadcast terrestrial or satellite television, the 60GHz wireless connectivity, and specific formats as HDMI signals are proposed and tested
Nguyen, Trung-Hiên. "Theoretical and experimental study of optical solutions for analog-to-digital conversion of high bit-rate signals". Thesis, Rennes 1, 2015. http://www.theses.fr/2015REN1S110/document.
Pełny tekst źródłaBi-dimensional modulation formats based on amplitude and phase signal modulation, are now commonly used in optical communications thanks to breakthroughs in the field of electronic and digital signal processing (DSP) required in coherent optical receivers. Photonic solutions could compensate for nowadays limitations of electrical circuits bandwidth by facilitating the signal processing parallelization. Photonic is particularly interesting for signal sampling thanks to available stable optical clocks. The heart of the present work concerns analog-to-digital conversion (ADC) as a key element in coherent detection. A prototype of linear optical sampling using an original solution for the optical sampling source, is built and validated with the successful equivalent time reconstruction of NRZ, QPSK and 16-QAM signals. Some optical and electrical limitations of the system are experimentally and numerically analyzed, notably the extinction ratio of the optical source or the ADC parameters (bandwidth, integration time, effective number of bits ENOB). Moreover, some new DSPs tools are developed for optical transmission using bi-dimensional modulation formats (amplitude and phase). Two solutions are proposed for IQ quadrature imbalance compensation in single carrier optical coherent transmission: an original method of maximum signal-to-noise ratio estimation (MSEM) and a new structure for joint compensation and equalization; these methods are experimentally and numerically validated with 16-QAM signals. Moreover, an improved solution for carrier recovery (frequency offset and phase estimation) based on a circular harmonic expansion of a maximum loglikelihood function is studied for the first time in the context of optical telecommunications. This solution which can operate with any kind of bi-dimensional modulation format signal is numerically validated up to 128-QAM. All the DSP tools developed in this work are finally used in a demonstration of a 10 Gbaud QPSK 100 km transmission experiment, featuring a strong non-linear phase noise limitation and regenerated using a phase preserving and power limiting function based on a photonic crystal nanocavity
Araujo, Viana Carlos. "Développement technologique et intégration système de VCSEL et HPT SiGe pour des applications radio-sur-fibre 60 GHz bas coût". Thesis, Paris Est, 2014. http://www.theses.fr/2014PEST1003/document.
Pełny tekst źródłaWireless communication technologies have become one of the most popular and indispensable part of people's lives in the recent years, offering mobility and services never before available from mobile communication until local network communication. This work is based on the frame of the French ORIGIN project and intended to explore the Home Area Network using the most recent Wi-Fi standard at 60 GHz with the goal to present a solution for the upcoming days where MultiGbit/s wireless communication will be required. The ORIGIN solution is characterized by the complementary action of two technologies: 60 GHz Wireless communication and Radio-over-Fiber (RoF) infrastructure. The project pretends to propose a real prototype based on RoF transducers and a Multipoint-to-Multipoint architecture to cover the entire house. This thesis covers from the single optoelectronic chip devices until the system implementation and the final demonstrator. The light source and the photodetector choice were very important since it dictated the RoF transducer architecture. Our choice was on 850 nm multimode devices (GaAs VCSEL and SiGe HPT) which allow relaxed constraints on the optical packaging and, therefore, low cost solutions. In terms of performances those devices are limited in a few tens of Gigahertz of bandwidth which was the reason for the intermediate frequency (IF) architecture. This thesis work addressed the electrical and optical interconnection of the optoelectronic chip devices. It explored the integration of hybrid amplification stages and passive networks within optoelectronic receivers and emitters. The optical packaging issues were addressed through a conventional coupling technique using a ball lens first. The die device performances were evaluated and compared with a packaged module in terms of frequency response, noise and nonlinearities. Since performances are usually measured as link performances we proposed a definition of the Opto-microwave figures of merit, such as Opto-microwave gain, noise, nonlinearities and EVM. They are presented and integrated into behavioral models, allowing both the individual performances extraction and system design. The integration of the RoF module in the system is the final part of this thesis. The performances were measured and simulated at each integration step. The final demonstrator based on the multipoint-to-multipoint architecture was implemented using an optoelectronic central node for the signal repartition and the Green Box for signal controlling. Real-time bidirectional transmission between two commercial WirelessHD devices at ~3 Gbit/s was validated. In a final section directions to improve VCSEL and SiGe HPT are explored. 25 GHz analogue VCSELs are explored with a focus on their dimensions, improved access and the potential of a suited matching approach. A novel collective and passive optical coupling technology is also proposed for both VCSEL and top illuminated detectors that couple smaller and faster devices
Holtz, Jürgen. "Codage pour les communications par fibres optiques /". Paris : Ecole nationale supérieure des télécommunications, 1994. http://catalogue.bnf.fr/ark:/12148/cb357781974.
Pełny tekst źródłaLethien, Christophe. "Étude et réalisation d'un transducteur et d'un système de transmission fibre multimode - radio à 850nm pour applications GSM, UMTS et WIFI". Lille 1, 2004. https://ori-nuxeo.univ-lille1.fr/nuxeo/site/esupversions/893b3cd1-ae6a-4f03-95cf-442695977ddc.
Pełny tekst źródłaSylvestre, Thibaut. "AMPLIFICATION ET CONVERSION PARAMETRIQUES, DECALAGE ET SUPPRESSION DE FREQUENCES PAR PROCESSUS KERR ET RAMAN DANS LES FIBRES OPTIQUES". Phd thesis, Université de Franche-Comté, 1999. http://tel.archives-ouvertes.fr/tel-00006109.
Pełny tekst źródłaPophillat, Lucien. "Transmission video par fibre optique". Limoges, 1987. http://www.theses.fr/1987LIMOA001.
Pełny tekst źródłaPophillat, Lucien. "Transmission vidéo par fibre optique". Grenoble 2 : ANRT, 1987. http://catalogue.bnf.fr/ark:/12148/cb37608975p.
Pełny tekst źródłaHanna, Marc. "Sources laser femtoseconde à fibre optique". Habilitation à diriger des recherches, Université Paris Sud - Paris XI, 2013. http://tel.archives-ouvertes.fr/tel-00806296.
Pełny tekst źródłaNeveux, Antoine Laurent. "Optoalimentation de capteurs par fibre optique". Nice, 1990. http://www.theses.fr/1990NICE4421.
Pełny tekst źródłaGrondin, Odile. "Vers un fluoroimmunocapteur à fibre optique". Vandoeuvre-les-Nancy, INPL, 1994. http://www.theses.fr/1994INPL078N.
Pełny tekst źródłaMoschim, Edson. "Contribution à la modélisation des composants photoniques et des systèmes de communication utilisant les fibres optiques en plastique comme support de transmission". Paris 11, 1989. http://www.theses.fr/1989PA112067.
Pełny tekst źródłaIn this work we present the modelisation and characterisation of photonic devices and plastic optical fiber transmission systems. A PMMA core plastic optical fiber is studied and a theorical and experimental analysis method of its material properties is proposed. Homojunction visible light emmiting diodes are also analysed. Their transmission properties such as optical power, bandwidth and spectra characteristics are calculated and measured. All these models are used in the analysis of a complet transmission system. The performance for an analog or digital signal transmission is evaluated according to the physical and technological parameters of the most important photonic and electronic devices
Bhatti, Ajaz. "D fibre antenna for microcellular communications". Thesis, Manchester Metropolitan University, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.252439.
Pełny tekst źródłaBeauchemin, Maryse. "Coupleur holographique auto-adapté pour fibre optique". Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2001. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/MQ61328.pdf.
Pełny tekst źródłaMedjadba, Hocine. "Optimisation d’un gyroscope à fibre optique multimode". Strasbourg, 2011. http://www.theses.fr/2011STRA6077.
Pełny tekst źródłaThe aim of the work presented in this thesis is to develop a new version of a multimode fiber optic gyroscope based on the optimal choice of the optical components and the signal processing. The work is mainly divided to two parts. The first part is devoted to the modeling of multimode Sagnac interferometer and allows the study of the effect of the modes coupling on the gyroscope performances. The modeling results are used to optimize the choice of the gyroscope components. The second part is dedicated to the experimental setup of the new prototype of the gyroscope and for the performances characterization
Castan, Stéphanie. "Codage de canal pour les communications optiques". Limoges, 2009. https://aurore.unilim.fr/theses/nxfile/default/ca31ecf8-c9ba-423d-93f5-ebe0d7929315/blobholder:0/2009LIMO4021.pdf.
Pełny tekst źródłaThe work done in this study focuses on forward error correction used to compensate for performance degradations in fiber optical links, mainly corrupted by the quadratic photo detection process. When we consider a single user transmission, this process has an impact on the photo detected signal statistic, which can be represented as a chi-square function. Taking into account this statistic, the iterative decoding used for LDPC codes is modified in order to optimise the performance. In the case including Optical Code Division Multiple Access, mainly disrupted by Multiple Access Interference, photo detection induces beatings called beat noise. Studying the photo detected signal statistic leads us to establish a theoretical model based on a mixture of chi-square distribution. The error correction performance has been optimised by taking into account this model in the decoding process, which permits considering an application to multimedia transmissions
Guillaumond, Didier. "Étude théorique et expérimentale d'une source à fibre optique dopée erbium pour un gyromètre à fibre optique hautes performances". Saint-Etienne, 2000. http://www.theses.fr/2000STET4009.
Pełny tekst źródłaTanzilli, Sébastien. "Optique Intégrée pour les Communications Quantiques". Phd thesis, Université de Nice Sophia-Antipolis, 2002. http://tel.archives-ouvertes.fr/tel-00008814.
Pełny tekst źródłaLe guide PPLN montre une efficacité de conversion supérieure à 10-6, correspondant à une amélioration de 4 ordres de grandeur par rapport aux générateurs massifs. Même pompé par de faibles puissances, il présente une probabilité significative de créer deux paires simultanément ce qui est un avantage essentiel pour certains protocoles de communication quantique. Nous proposons à cet effet deux méthodes de caractérisation de la probabilité de créer une paire par photon de pompe (régime continu) ou par impulsion laser.
Afin d'examiner la qualité des états enchevêtrés, deux expériences d'interférométrie ont montré des taux de contraste respectifs de 97 % et de 84 % pour les intrications en énergie-temps et en time-bins. Bien que ce dernier taux puisse être amélioré, ces résultats montrent le fort potentiel des guides PPLN pour devenir l'un des éléments clés des futurs protocoles de communication quantique.
Rzaigui, Habeb. "Systèmes hybrides opto/sans fil pour les réseaux multi-gigabits aux fréquences millimétriques". Thesis, Université Grenoble Alpes (ComUE), 2016. http://www.theses.fr/2016GREAT014/document.
Pełny tekst źródłaThis thesis focuses on the radio-over-fiber (RoF) communication systems at millimeter frequencies in the frequency range 57-66 GHz and optical generation of a signal at millimeter-wave frequency band. The technique used is based on mode-locked laser diodes. The diodes employed in this work are in quantum dots (or quantum dashes) technology. In this thesis, several studies were conducted: the first relates the ability of integration these types of lasers in the RoF communication systems under direct or external modulation. The second study was devoted to propagation effects. An original technique was implemented to reduce the sensitivity to chromatic dispersion in an optical fiber. A study of the reduction of phase noise mode-locked lasers based on the observation of the reaction effect and against the external optical injection was presented
Zaganiaris, Alcibiade. "Contribution à l'évolution des techniques des communications optiques : des composants aux systèmes opérationnels". Lyon 1, 1991. http://www.theses.fr/1991LYO19002.
Pełny tekst źródłaAlegria, Carlos Feio Gama. "All-fibre devices for WDM optical communications". Thesis, University of Southampton, 2001. https://eprints.soton.ac.uk/30238/.
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