Αυτή η εργασία ασχολείται με το σχεδιασμό των μητροπολιτικών ευρυζωνικών δικτύων οπτικών ινών και ειδικότερα αυτών που δημιουργούνται στην Ελλάδα. Γίνεται η ανάλυση των τεχνολογιών και τεχνικών υλοποίησης τους. Στη συνέχεια παρουσιάζονται τα γεωγραφικά συστήματα πληροφοριών (GIS) που αποτελούν ένα ισχυρό εργαλείο στη σχεδίαση, μελέτη και επέκταση των δικτύων. Επιλύεται το πρόβλημα υπολογισμού αποστάσεων από σημείο σε σημεί ο μιας οπτικής ίνας στο GIS που θα διευκολύνει τη μελέτη και το σχεδιασμό του δικτύου. Με τη χρήση του GIS συστήματος arcgis γίνεται η ψηφιακή χαρτογράφηση του μητροπολιτικού δικτύου οπτικών ινών της Πάτρας όπως αυτό πρόκειται να υλοποιηθεί στα επόμενα χρονιά. Παρουσιάζεται μια μελέτη που θα κάνει αυτόματη τη διαδικασία σχεδίασης των υποδομών του δικτύου και τη συνεχή επέκταση του με το μικρότερο δυνατό κόστος με τη βοήθεια των γεωγραφικών συστημάτων πληροφορίας. Στη συνέχεια υλοποιείται ξανά η ψηφιακή χαρτογράφηση του μητροπολιτικού δικτύου οπτικών ινών της Πάτρας αυτή τη φορά με το μοντέλο αυτόματης σχεδίασης δικτύου που παρουσιάστηκε και γίνεται η σύγκριση του με το πραγματικό δίκτυο που υλοποιείται στην Πάτρα. / -

Η έντονη τάση για συνεχή επικοινωνία και μετάδοση πληροφορίας, οδηγεί στην ανάγκη για αύξηση των τηλεπικοινωνιακών υπηρεσιών. Γι’ αυτό η προσπάθεια εύρεσης λύσης και νέων δρόμων για την εξυπηρέτηση των τηλεπικοινωνιακών αναγκών αποτελεί βασικό στόχο και σκοπό. Η οπτική ίνα είναι ο πιο αξιόπιστος τρόπος για την μετάδοση δεδομένων. Τα πλεονεκτήματα της οπτικής ίνας, καθώς και το γεγονός ότι υπερτερεί του χάλκινου αγωγού, οδηγεί στην εξ’ ολοκλήρου αντικατάσταση του δεύτερου από την ίνα. Οι οπτικές ίνες καλύπτουν τις ανάγκες για αύξηση των ταχυτήτων μετάδοσης και παρουσιάζουν μεγάλο εύρος ζώνης. Το 1854 διατυπώθηκε η αρχή της ολικής ανάκλασης από τον John Taydall, , με βάση την οποία λειτουργεί η οπτική ίνα και το 1950, πήρε την πρώτη της μορφή με την ανάπτυξη της γυάλινης ίνας με ένα είδος επιχρίσματος (glass – coated fiber). Τότε χρησιμοποιήθηκε για πρώτη φορά ο όρος «fiber optics» (οπτική ίνα). Έπειτα, το 1990 εξαπλώθηκε η χρήση της σε τηλεπικοινωνιακά δίκτυα. Τα πλεονεκτήματα των οπτικών ινών και δικτύων πυροδότησαν ισχυρά κίνητρα, ώστε οι Εταιρείες Ηλεκτρικής Ενέργειας να επιθυμούν να εισέλθουν στην τηλεπικοινωνιακή αγορά και να διεκδικήσουν μερίδιο από αυτήν. Σκοπός της διπλωματικής εργασίας είναι η αναφορά στις εξελίξεις της τεχνολογίας των οπτικών ινών που μπορούν να προσφέρουν λύση με την εφαρμογή τους σε γραμμές υψηλής τάσης συνδυάζοντας απαιτήσεις ασφάλειας, κόστους και ποιότητας που είναι απαραίτητες για τις τηλεπικοινωνιακές ή ενεργειακές υπηρεσίες. Η διπλωματική εργασία απευθύνεται σε άτομα τα όποια αναζητούν μια συνολική εικόνα των τεχνικών λύσεων στην τεχνολογία των οπτικών, οι οποίες ενσωματώνονται σε γραμμές υψηλής τάσης. Στόχος της είναι να εξοικειώσει τον αναγνώστη με τις έννοιες της οπτικής ίνας, να του δώσει το απαραίτητο υπόβαθρο για την κατανόησή τους και μέσα από την ανάλυση των τεχνικών λύσεων, που περιγράφονται στην εργασία αυτή, να του παρουσιάσει τα χαρακτηριστικά των οπτικών καλωδίων καθώς και τους νέους ορίζοντες που ανοίγονται από την εφαρμογή των οπτικών καλωδίων σε γραμμές ισχύος. Στο δεύτερο κεφάλαιο δίνονται οι ορισμοί και βασικές έννοιες των οπτικών ινών. Παρουσιάζονται οι τύποι των οπτικών ινών διακρίνοντάς τις σε μονότροπες, πολύτροπες ίνες βηματικού δέκτη, πολύτροπες ίνες βαθμιαίου δέκτη, ανάλογα με την κατανομή του δείκτη διάθλασης. Αναφέρονται τα χαρακτηριστικά και οι επιδόσεις κάθε τύπου οπτικών ινών. Επίσης γίνεται μια εκτενής αναφορά στην κατασκευή και στα υλικά των ινών. Οι διαδικασίες κατασκευής είναι η διεργασία OVPO- Πλευρική εναπόθεση, διεργασία OVPO- Αξονική εναπόθεση (VAD), διεργασία MCVD ή IVPO, διεργασία PCVD και η διεργασία απευθείας τήξης. Περιγράφεται η αρχή λειτουργίας της οπτικής ίνας και αναφέρονται τα μηχανικά χαρακτηριστικά της, εφόσον τα οπτικά καλώδια υποβάλλονται σε μικροκάμψεις, τάσεις εφελκυσμού και παραμορφώσεις. Τέλος αναφέρονται αναλυτικώς, τα πλεονεκτήματα και τα μειονεκτήματα των οπτικών ινών. Το τρίτο κεφάλαιο αποτελεί την πρώτη ενότητα όσον αφορά στην ανάλυση του οπτικού καλωδίου. Παρουσιάζονται τα μέρη από τα οποία αποτελείται, τα υλικά από τα οποία κατασκευάζονται τα μέρη αυτά καθώς και οι ιδιότητες των υλικών, όπως μηχανικές και θερμικές ιδιότητες καθώς και επιδράσεις με αλλά υλικά. Επίσης παρουσιάζονται οπτικά και μηχανικά χαρακτηριστικά που έχουν άμεση σχέση με τα υλικά των καλωδίων. Τέλος, δίνονται και διάφορες τεχνικές λύσεις αναφορικά με τα μέρη του καλωδίου και τα χαρακτηριστικά του. Στο τέταρτο κεφάλαιο αναφέρονται αναλυτικά οι τεχνολογίες οπτικών ινών σε γραμμές υψηλής τάσης. Κατηγοριοποιούνται σε οπτικά καλώδια για εναέριες γραμμές υψηλής τάσης, οπτικές ίνες συγχωνευμένες σε υποβρύχια καλώδια και υπόγεια καλώδια. Αναλύονται ξεχωριστά τα οπτικά καλώδια για εναέριες γραμμές, δηλαδή ο οπτικός αγωγός γείωσης (OPGW), τα προσαρτημένα καλώδια (OPAC) και τα αυτοφερόμενα καλώδια (ADSS). Περιγράφεται κάθε οπτικό καλώδιο ξεχωριστά και αναφέρονται οι διάφοροι τύποι κατασκευών κάθε καλωδίου, τα ηλεκτρικά και μηχανικά τους χαρακτηριστικά καθώς , η εγκατάστασή τους και οι απαραίτητες ενέργειες για την προστασία τους. Δίνεται ο παρελκόμενος εξοπλισμός των εναέριων οπτικών καλωδίων, και τα είδη των εξαρτημάτων που χρησιμοποιούνται. Στις δυο τελευταίες ενότητες του κεφαλαίου αναφέρονται έρευνες της CIGRE και γίνεται μια προσπάθεια τεχνικής και οικονομικής σύγκρισης των οπτικών καλωδίων. Στο κεφάλαιο πέντε διακρίνονται 28 παράμετροι, σε παραμέτρους εγκατάστασης και περιβαλλοντικές παραμέτρους, ώστε να είναι επιτυχής η εγκατάσταση οπτικών καλωδίων. Για κάθε παράμετρο δίνονται τυπικές τιμές που αναφέρονται σε κάθε πιθανή εφαρμογή των οπτικών καλωδίων καθώς και πρακτικά παραδείγματα για κάθε περίπτωση. Επίσης με βάση αυτές τις παραμέτρους περιγράφονται τροποποιήσεις που γίνονται για την προστασία τους. Στο κεφάλαιο έξι γίνεται αναφορά στην σημερινή κατάσταση στην Ελλάδα όσον αφορά στην εφαρμογή των οπτικών καλωδίων στις γραμμές ισχύος καθώς και οι μελλοντικές κατευθύνσεις. Δίνονται τα πλεονεκτήματα της ΔΕΗ μέσω των οποίων υπερτερεί έναντι των άλλων εταιρειών, για την είσοδό της στην τηλεπικοινωνιακή αγορά. Αναλύεται η θέση της ΔΕΗ στην αγορά αυτή και η ανάπτυξη του δικτύου της Τellas. Τέλος, η διπλωματική εργασία ολοκληρώνεται με το Παράρτημα Α, στο οποίο αναφέρονται μερικοί τύποι υπόγειων και εναέριων οπτικών καλωδίων από σελίδες εταιρειών που διαθέτουν αυτά τα προϊόντα στην αγορά. / The continuous tendency for communication and transmission of information leads to the increase of services in telecommunications. Therefore, the effort of finding an effective solution for these services is more than necessary. The technology of fiber optics is the most reliable way of transmitting data. The fact that, optical fibers have many advantages and are better than the conductor by coper, has led to the replacement of wires by coper with optical fibers. Nowadays, fiber optics fulfill the demand of increase of transmission rate and bandwith. In 1854, John Taydall was the first to formulate the law of total reflection and in 1950 was developed a glass – coated fiber and for the first time the term “fiber optics” was used. Inevitably later, the spread of fiber optics in networks was a fact. Fiber optics are so effective that, many electrical companies want to enter in the market of telecommunications. The purpose of this work initially, is to describe and define fiber optics. Then the technologies of fiber optics, that serve telecommunications are to be mentioned and especially the technology of applying optical fibers in AC lines. Furthermore, we will mention the situation of these technologies in Greece and we will discuss its future. The definitions and different types of fiber optics are given in the second chapter. The fiber optics are divided into singlemode, multimode stepindex and multimode gradedindex fibers. Furthermore, the characteristics of the manufacturing of an optical cable are presented. In this chapter, are mentioned the OVPO process, the VAD process, the MCVD or IVPO process, the OCVD process and the process of instant fusion. Later, the description of how an optical fiber works is given and its mechanical features are mentioned. Finally, the advantages and disadvantages of fiber optics are presented. The analysis of optical cable comes first in chapter three. The layers of an optical fiber are presented and also the materials and their mechanical, thermic and chemical attributes. Finally, some technical solutions are given related to the layers and features of the cable. The technologies of applying optical fibers in AC lines are being described in the fourth chapter. The optical cables for overhead lines are divided and analyzed separately. That is to say, Optical Ground Wire (OPGW), Optical Attached Cable (OPAC), and All – Dielectric Self – Supporting optical cable (ADSS). Also, undersea and underground cables are mentioned. In this part, the mechanical and electrical features of each cable are described and also their installation and protection. Moreover, the equipment of the overhead optical cable and its elements. Finally, the optical cables are compared, in order to facilitate the choice between them. In chapter five, an effort is being showed to present a schedule for the successful installation of optical cables. This plan includes the division of parameters in installation and environmental parameters. This chapter also includes examples and practical applications for each parameter. In the end modifications of an optical cable are presented in order to secure its protection. The state in Greece, nowadays is being described in sixth chapter. The last chapter presents the application of optical cables in AC lines in this country and the role that plays the national electricity company in the market of telecommunications. Also the future prospects are being analyzed. In the last part of this work many different types of optical cables are presented, that exist in the market of telecommunications.

This dissertation studies a unique delta sigma modulator (DSM), known as reversed hysteresis delta sigma modulator (R-HDSM). This modulator is appropriate for ultra-high speed analog-to-digital converters, which can be used for communications and signal processing systems and their applications. Furthermore, the procedure to design the binary delta sigma modulator (BDSM) with a delay is developed and then parameters deltaOFF and deltaON ; are calculated for the system. In addition, analysis of the BDSM with a delay is achieved and the theoretical and simulated values compared. The reversed hysteresis delta sigma modulators are also analyzed, and the theoretical and the simulated values compared. The dissertation evaluates the performance measure for the suggested systems with continuous DSM and BDSM in terms of the spurious free dynamic range (SFDR), the signal to noise ratio (SNR), and the root mean square error (RMS). It studies the second-order R-HDSM. Finally, it compares the first-order R- HDSM and the second-order R-HDSM in terms of the signal to noise ratio (SNR).

The creation of optical states of light that are quantum mechanical in nature in optical fibers is discussed and demonstrated experimentally. Specifically, two- photon states created by spontaneous four-wave-mixing in commercially available single-mode, birefringent fibers are studied. When creating photon states of light, it is important to verify the created states are of the proper photon number distribution and free of noise. We detail a method for combining thresholding, non-number resolving detectors to characterize the photon number distribution created via SFWM and a procedure to quantify the noise sources present in the process. Frequency translation in optical fibers with two-photon states is discussed and experimental considerations are presented.

Neste trabalho é apresentado um sistema de leitura de redes de Bragg derivado da técnica por filtro Fabry-Perot sintonizável. A técnica apresentada é implementada através de um sistema atuador piezelétrico que modula mecanicamente uma rede de Bragg de referência, com seu espectro de reflexão convoluido com o espectro de reflexão de uma rede sensora. A técnica desenvolvida apresenta vantagens em relação ao processo original por ter implementação mais simples, menor custo e melhor discriminação de posição espectral. / This work presents a process to detect Bragg grating spectra based on the tunable Fabry Perot filter technique. The apparatus is assembled with a piezoelectric actuator that mechanically modulates a reference Bragg grating. The spectrum of that grating is convoluted with the spectrum of the sensor during a sweep. The device presents some advantages as, eg., simplicity, lower cost and better discrimination for the spectral position of the reflected band.

Este trabalho apresenta a análise temporal do deslocamento do comprimento de onda de Bragg baseada na teoria da elastodinâmica linear e na teoria viscoelástica. As soluções exatas para o modelo de uma fibra engastada são encontradas a fim de estimar a máxima velocidade de sintonização quando forças de tração são aplicadas na extremidade livre da fibra. É feita a comparação entre a fibra monomodo de sílica e a fibra monomodo polimérica mostrando as diferenças do tempo de resposta, velocidade de sintonização e deslocamento de onda de Bragg quando a mesma carga longitudinal é aplicada. Também apresenta a resposta transiente e permanente para o método Modos Assumidos, com aplicação potencial em estruturas submetidas a cargas harmônicas longitudinais, com massa e rigidez concentradas e seção transversal variável. Usando a combinação entre os métodos modos assumidos e matriz de transferência, simulações foram feitas para um modulador acusto-óptico, baseado em redes de Bragg em fibra, quando uma carga harmônica é aplicada. O espectro resultante e a duração do regime transiente são calculados e comparados com resultados experimentais relatados na literatura. Além disso, este trabalho apresenta um sintonizador de redes de Bragg, baseado no princípio da mola de entalhe, que permite a magnificação do deslocamento provocado por um atuador piezoelétrico através da tração em um pedaço de fibra. O tempo de resposta é encontrado experimentalmente para diferentes casos de amortecimento. / This work presents the time analysis of the Bragg wavelength shift in fiber gratings based on the elastodynamics theory and viscoelastic theory. The model is valuable for estimating the maximum tuning speed when traction forces are apllied to the free end of the grating. A comparison between single mode silica optical fiber and polymer optical fiber is performed showing the differences of time response, tuning speed and Bragg wavelength shift when the same longitudinal load is applied on both types of fibers. Also presents the transient and steady state solutions for Assumed Modes method, with potential application on general structures under harmonic longitudinal loads, with mass and stiffness concentrated and variable cross section. Using the combined Assumed Modes and Matrix Transfer method, simulations results were performed on a Bragg grating acousto-optic modulator when a harmonic load is applied. The resulting spectrum and the transient duration were calculated and compared with experimental results related by literature.Furthermore, this work presents a mechanism tuning FBGs, based on a notch type spring principle, which magnifies the displacement of a piezoelectric element stretching a piece of fiber optic. Time response is experimentally acessed for different damping situations of the notch type spring.

Made available in DSpace on 2016-03-15T19:37:37Z (GMT). No. of bitstreams: 1 FAUSTO_MIZUTANI_ENG.pdf: 975527 bytes, checksum: 1384f3ad6af75b99bf9eaa01b7a2fc3a (MD5) Previous issue date: 2006-08-29 / The performance of a distributed Raman amplifier at C and S bands using the TrueWave Reach LWP fiber in 100 km span is analyzed through numerical simulations. The physical parameters of the fiber, such as, attenuation, dispersion, and Raman gain efficiency for C and S bands were experimentally characterized by the manufacturer, the OFS Denmark. It is required around four pumping lasers to assure an on-off gain of approximately 15dB in 70nm (1500nm to 1570nm), covering operation in the C and S band. / O desempenho de uma amplificador Raman distribuído na banda C e S utilizando a fibra TrueWave Reach LWP em 100 km de enlace é analisado através de simulações numéricas. Os parâmetros físicos da fibra, como atenuação, dispersão, e eficiência de ganho Raman para bandas C e S foram caracterizados experimentalmente pelo fabricante, a OFS Denmark. Em torno de quatro lasers de bombeamento são necessários para garantir um ganho on-off da ordem de 15dB em 70nm (1500nm a 1570nm), cobrindo a operação na banda C e S.

M.Ing. / This thesis demonstrates the measurement of temperature distribution across a metal plate and the non-contact measurement of torsion in a rotating shaft. After a thorough theoretical study of the origin of fibre Bragg gratings, methods of fabrication and erasing of gratings, methods of demodulating the signals from gratings, and methods of discriminating between strain and temperature variations in gratings, simulations and experiments were done to prove the feasibility of both temperature distribution measurement and non-contact torsion measurement. For the measurement of temperature distribution, a 450 x 450 x 1.6 mm type 304 stainless steel plate was used. Two 4,7Ω 25W resistors were used as heat sources, and five fibre Bragg gratings measured the temperature at strategic points on the plate. The measured values were interpolated appropriately and a three-dimensional representation of the temperature distribution was shown on a personal computer monitor. The measurement of torsion was first done on a non-rotating 25 mm diameter solid shaft with torque applied. Both resistive strain gauges and fibre Bragg gratings were attached to the shaft and the measurement results compared well. Up to 90 Nm of torque was applied to the shaft. The non-contact measurement of torsion on a rotating shaft was done with fibre Bragg gratings and involved the use of graded index (GRIN) lenses for transmitting optical information between the light source, the gratings, and back to the spectrum analyser through free space. A special Böhler steel with high yield strength was used, and the set-up was mounted on a lathe. The one end of the shaft was clamped in the lathe chuck, and the other was fixed to an automobile drum brake system, allowing the application of torque on the rotating shaft. Up to 97 Nm of torque was applied to the shaft rotating at 190 rpm, and the results are within 10% of the expected values. As far as we are aware, this is the first time that torsion is measured by fibre Bragg gratings without the need to have physical contact with the shaft, i.e. slip rings, to transmit the information to and from the sensors. The experimental results of this thesis confirm that fibre Bragg grating sensors can be applied usefully in temperature distribution measurement, as well as in the measurement of torsional stress in rotating shafts.

Proactive and nondisruptive channel probing is investigated for the measurement of channel power, amplifier channel gain, and optical signal-to-noise ratio (OSNR) without disrupting established wavelength-division multiplexed channels. Using a nondisruptive probe signal over a three-span link, wavelength switching-induced power excursions are predicted to be within +/- 0.2 dB, and OSNR as high as 20 dB is accurately measured with a maximum of 0.5 dB error.

The ever-increasing demand for broadband services by end-user devices utilising 3G/4G/LTE and the projected 5G in the last mile will require sustaining broadband supply from fibre-linked terminals. The eventual outcome of the high demand for broadband is strained optical and electronic devices. The backbone optical fibre transport systems and techniques such as dense wavelength division multiplexing (DWDM), higher modulation formats, coherent detection and signal amplification have increased both fibre capacity and spectrum efficiency. A major challenge to fibre capacity and spectrum efficiency is fibre-faults and optical impairments, network management, routing and wavelength assignment (RWA). In this study, DWDM and flexible spectrum techniques such as wavelength assignment and adjustment, wavelength conversion and switching, optical add and drop multiplexing (OADM) and bitrate variable transmission have been experimentally optimized in a laboratory testbed for short- and long-haul optical fibre networks. This work starts by experimentally optimising different transmitters, fibre-types and receivers suitable for implementing cost effective and energy efficient flexible spectrum networks. Vertical cavity surface-emitting lasers (VCSELs) and distributed feedback (DFB) lasers have been studied to provide up to 10 Gb/s per channel in 1310 nm and 1550 nm transmission windows. VCSELs provide wavelength assignment and adjustment. This work utilises the non-return-to-zero (NRZ) on-off keying (OOK) modulation technique and direct detection due to their cost and simplicity. By using positive intrinsic negative (PIN) photo-receivers with error-free BER sensitivity of -18±1 dBm at the acceptable 10-9-bit error rate (BER) threshold level, unamplified transmission distances between 6 km and 76 km have been demonstrated using G.652 and G.655 single mode fibres (SMFs). For the first time, an all optical VCSEL to VCSEL wavelength conversion, switching, transmission at the 1550 nm window and BER evaluation of a NRZ data signal is experimentally demonstrated. With VCSEL wavelength conversion and switching, wavelength adjustments to a spectrum width of 4.8 nm (600 GHz) can be achieved to provide alternative routes to signals when fibre-cuts and wavelength collision occurs therefore enhancing signal continuity. This work also demonstrates a technique of removing and adding a wavelength in a bundle of DWDM and flexible channels using an OADM. This has been implemented using a VCSEL and a fibre Bragg grating (FBG) providing a wavelength isolation ratio of 31.4 dB and ~0.3 𝑑𝐵 add/drop penalty of 8.5 Gb/s signal. As a result, an OADM improves spectrum efficiency by offering wavelength re-use. Optical impairments such as crosstalk, chromatic dispersion (CD) and effects of polarization mode dispersion (PMD) have been experimentally investigated and mitigated. This work showed that crosstalk penalty increased with fibre-length, bitrate, interfering signal power and reduced channel spacing and as a result, a crosstalk-penalty trade-off is required. Effects of CD on a transmitted 10 Gb/s signal were also investigated and its mitigation techniques used to increase the fibre-reach. This work uses the negative dispersion fibres to mitigate the accumulated dispersion over the distance of transmission. A 5 dB sensitivity improvement is reported for an unamplified 76 km using DFB transmitters and combination of NZDSF true-wave reduced slope (TW-RS) and submarine reduced slope (TW-SRS) with + and – dispersion coefficients respectively. We have also demonstrated up to 52 km 10 Gb/s per channel VCSEL-based transmission and reduced net dispersion. Experimental demonstration of forward Raman amplification has achieved a 4.7 dB on-off gain distributed over a 4.8 nm spectral width and a 1.7 dB improvement of receiver sensitivity in Raman-aided 10 Gb/s per wavelength VCSEL transmission. Finally, 4.25-10 Gb/s PON-based point to point (P2P) and point to multipoint (P2MP) broadcast transmission have been experimentally demonstrated. A 10 Gb/s with a 1:8 passive splitter incurred a 3.7 dB penalty for a 24.7 km fibre-link. In summary, this work has demonstrated cost effective and energy efficient potential flexible spectrum techniques for high speed signal transmission. With the optimized network parameters, flexible spectrum is therefore relevant in short-reach, metro-access and long-haul applications for national broadband networks and the Square Kilometre Array (SKA) fibre-based signal and data transmission.