Dissertations / Theses on the topic 'Broadband fiber optic links'

In digital communication systems, several types of impairments may be introduced to the signal. These impairments result in degraded system performance; for example, high bit-error-rate or power penalty. For optical communication systems, in this thesis, these impairments are categorized into four types; that is, thermal noise, shot noise, signal-dependent noise, and intersymbol interference (ISI). By using a Gaussian approximation, effects of the first three impairments are analyzed. It is shown that signal-dependent noise introduces an error floor to the system and the bit-error-rate is considerably degraded if a nonzero-extinction ratio is applied to the system. It is shown that if the decision threshold at the decision circuit is set improperly, more received power is required to keep the bit-error-rate constant. Three main components in the system (i.e., transmitter, optical fiber, and receiver) are modeled as Butterworth filters. ISI from this model is determined by computer simulation. A high ISI is from a small system bandwidth. It is shown that a minimum power penalty can be achieved if the transmitter and receiver bandwidths are matched and fixed, and the ratio of fiber bandwidth to bit rate is 0.85. Comparing ISI from this model to ISI from raised cosine- rolloff filters, it is shown that at some particular bandwidths ISI from raised cosine-rolloff filters is much lower that that from this model. However, if the transmitter and receiver bandwidths are not matched and are not equal to these bandwidths, ISI from this model is lower than ISI from raised cosine-rolloff filters.<br>Master of Science

International Telemetering Conference Proceedings / November 04-07, 1991 / Riviera Hotel and Convention Center, Las Vegas, Nevada<br>This paper will present the results of an investigation of the feasibility of using broadband analog fiber optic technology to send telemetry antenna outputs from remote sites to a central site. The fiber optic hardware consisted of a prototype analog fiber optic transmitter and receiver plus 10 km of single-mode fiber. Laboratory tests were performed to simulate the performance in the real-world. The fiber optic system had a noise figure of 33.5 dB and a third order intercept point of 16.75 dBm. The use of this fiber optic system to transmit a 215-320 MHZ telemetry antenna downconverter output over a 10 km fiber would only degrade the quality of real-world telemetry signals by a few tenths of a decibel. Key words: analog fiber optic transmission, remote telemetry antennas.

A method to predict modal noise in short distance (30 m), high temporal bandwidth (hundreds of MHz) multimode optical links is proposed. In order to accommodate low cost, mechanical alignment, the link medium is modified from single mode fiber (used routinely in telecommunication systems) to multimode fiber. Modal dispersion in multimode fiber calls for a reduction in link length to preserve a relatively high temporal bandwidth. The source is a vertical cavity surface emitting laser (VCSEL), which is well suited for the high packaging density, high temporal bandwidth, and low power dissipation requirements of short distance optical communication systems. Coherence properties of several different types of VCSELs are experimentally examined with constant and modulated injection current with a bandwidth typical of that used in data communications systems. A fluctuation in the spatial irradiance output pattern of the VCSEL is identified as the dynamic component responsible for significant modal noise effects. The effect of finite system coherence length has been applied to the simulation process. The reduction in output fiber face speckle contrast, due to a broader source power spectrum and/or due to fiber modal dispersion with increasing fiber length, mitigates the effect of modal noise in the transmission link.

The use of analog fiber optic links for microcellular mobile radio comminications has been the focus of considerable research recently. These systems have the advantages relative to coaxial cable of low noise and enormous bandwidth. Analog subcarrier multiplexing techniques are used for transmitting the mobile signals over the fiber. Use of this technology however presents some unique problems due to the nonlinearities of the fiber optics system and the noise introduced by it. In this thesis, we analyse the dynamic range of the fiber links used for these applications. <p>The dynamic range is limited by the noise and the nonlinear distortion introduced by the fiber link. The main sources of nonlinear distortion are threshold clipping, gain saturation of the laser, and the combination of laser chirp and fiber dispersion. We have analytically modeled these nonlinearities and used these models to understand the dependence of the nonlinear distortion on the physical parameters of the laser diode and the fiber and also on the modulation index per channel and the number of channels. The performance of the 1S- 19 AMPS signals and the IS-54IDMA signals in the presence of fiber link noise is also discussed. Finally, the dynamic range of the fiber link for both AMPS and IDMA signals has been analyzed. The dynamic range of the fiber link is limited by the threshold clipping nonlinearity. It is also highly dependent on the number of mobile signals that are being communicated over the fiber link.<br>Master of Science

[ES] Las comunicaciones ópticas inalámbricas (OWC) constituyen una tecnología muy prometedora para el desarrollo de futuras comunicaciones inalámbricas. De hecho, ha despertado un interés creciente entre los investigadores y varias empresas de todo el mundo trabajan actualmente en el desarrollo de redes inalámbricas de muy alta velocidad. Las comunidades científica e industrial consideran la OWC como una tecnología complementaria en sus diversas formas: comunicaciones ópticas en el espacio libre (FSO), comunicaciones de luz visible (VLC) o fidelidad de la luz (Li-Fi). El espectro óptico ha sido considerado durante muchos años como una gran oportunidad para las comunicaciones inalámbricas, especialmente debido a la saturación del espectro de radiofrecuencia (RF). Esta disertación trata del uso de fuentes de banda ancha en sistemas de transmisión de luz visible (VLC), así como en sistemas de transmisión en el espectro infrarrojo por fibra óptica. En el trabajo de investigación realizado se pueden distinguir tres partes: En la primera parte, se considera el estudio y la simulación de componentes de Diodos Emisores de Luz (LED) con el software WIEN2k centrándose en las propiedades ópticas y eléctricas de los elementos II-VI. La segunda parte trata del diseño, la implementación y las pruebas de diferentes prototipos de comunicación VLC para la transmisión analógica y digital en modo simplex y semidúplex. Hemos demostrado un sistema OWC empleando una fuente de banda ancha (LED) para la transmisión no sólo de datos, sino también para la transmisión inalámbrica de energía. Además, se aborda el problema de la sincronización y la detección del nivel "1" o "0" de un bit en los sistemas de comunicación inalámbrica óptica implementados que surge como consecuencia de la atenuación de la luz a lo largo de la distancia y al problema de la pérdida de línea de visión (NLOS) entre el emisor y el receptor. Para hacer frente a este problema, se ha proporcionado un protocolo de comunicación que garantiza la transmisión fiable de datos digitales con un algoritmo de detección de nivel de bits adaptativo y se ha demostrado su eficacia mediante la transmisión de textos e imágenes. Además, esta tesis aporta una solución para la implementación de transmisores multiplexados en redes con división de longitud de onda (WDM) para formatos de modulación con multiplexación por división de frecuencia ortogonal (OFDM) basados en el uso de fuentes de banda ancha en el espectro infrarrojo para redes de fibra bidireccionales centralizadas. A pesar de las limitaciones impuestas por la dispersión cromática en el uso de este tipo de fuentes ópticas, la inclusión de ciertas estructuras antes de la detección permite la transmisión de señales OFDM en enlaces ópticos. En este trabajo se ha demostrado experimentalmente la reutilización de portadoras, la asignación dinámica de ancho de banda y la transmisión de señales OFDM multibanda mediante el uso de fuentes ópticas de banda ancha en redes WDM. Los principales resultados obtenidos en cada parte de esta tesis doctoral muestran los procedimientos de estudio, la eficacia de las soluciones propuestas y las limitaciones encontradas.<br>[CA] Les comunicacions òptiques sense fils (OWC) constitueixen una tecnologia molt prometedora per al desenvolupament de futures comunicacions sense fils. De fet, ha despertat un interés creixent entre els investigadors i diverses empreses de tot el món treballen actualment en el desenvolupament de xarxes sense fils de molt alta velocitat. Les comunitats científica i industrial consideren la OWC com una tecnologia complementària en les seues diverses formes: comunicacions òptiques en l'espai lliure (FSO), comunicacions de llum visible (VLC) o fidelitat de la llum (Li-Fi). L'espectre òptic ha sigut considerat durant molts anys com una gran oportunitat per a les comunicacions sense fils, especialment a causa de la saturació de l'espectre de radiofreqüència (RF). Aquesta dissertació tracta de l'ús de fonts de banda ampla en sistemes de transmissió de llum visible (VLC), així com en sistemes de transmissió en l'espectre infraroig per fibra òptica. En el treball de recerca realitzat es poden distingir tres parts: ¿ En la primera part, es considera l'estudi i la simulació de components de Díodes Emissors de Llum (LED) amb el software WIEN2k centrant-se en les propietats òptiques i elèctriques dels elements II-VI. ¿ La segona part tracta del disseny, la implementació i les proves de diferents prototips de comunicació VLC per a la transmissió analògica i digital de manera simplex i semidúplex. Hem demostrat un sistema OWC emprant una font de banda ampla (LED) per a la transmissió no sols de dades, sinó també per a la transmissió sense fil d'energia. A més, s'aborda el problema de la sincronització i la detecció del nivell "1" o "0" d'un bit en els sistemes de comunicació sense fil òptica implementats, que sorgeix a conseqüència de l'atenuació de la llum al llarg de la distància i al problema de la pèrdua de línia de visió (NLOS) entre l'emissor i el receptor. Per a fer front a aquest problema, s'ha proporcionat un protocol de comunicació que garanteix la transmissió fiable de dades digitals amb un algorisme de detecció de nivell de bits adaptatiu i s'ha demostrat la seua eficàcia mitjançant la transmissió de textos i imatges. ¿ A més, aquesta tesi aporta una solució per a la implementació de transmissors multiplexats en xarxes amb divisió de longitud d'ona (WDM) per a formats de modulació amb multiplexació per divisió de freqüència ortogonal (OFDM) basats en l'ús de fonts de banda ampla en l'espectre infraroig per a xarxes de fibra bidireccionals centralitzades. Malgrat les limitacions imposades per la dispersió cromàtica en l'ús d'aquest tipus de fonts òptiques, la inclusió d'unes certes estructures abans de la detecció permet la transmissió de senyals OFDM en enllaços òptics. En aquest treball s'ha demostrat experimentalment la reutilització de portadores, l'assignació dinàmica d'amplada de banda i la transmissió de senyals OFDM multibanda mitjançant l'ús de fonts òptiques de banda ampla en xarxes WDM. Els principals resultats obtinguts en cada part d'aquesta tesi doctoral mostren els procediments d'estudi, l'eficàcia de les solucions proposades i les limitacions trobades.<br>[EN] Optical wireless communication (OWC) is a very promising technology for future wireless communications developments. It has attracted increasing interest from researchers and several companies around the world are currently working on the development of very high-speed wireless networks. The scientific and industrial communities believe that OWC will be a complementary technology in its various forms: Free Space Optical communications (FSO), Visible Light Communications (VLC), Light Fidelity (Li-Fi). In fact, the optical spectrum has been considered for many years as a great opportunity for wireless communications especially due to the saturation of the radio frequency (RF) spectrum. This dissertation deals with the use of broadband sources in visible light transmission systems (VLC) as well as fiber optic systems. To carry out the research, three parts can be distinguished: In the first part, we consider the study and simulation of Light Emitting Diode (LED) components with the WIEN2k software by focusing on the optical and electrical properties of elements II-VI. The second part deals with the design, implementation and testing of different VLC communication prototypes for analog and digital transmission in simplex and half-duplex mode. We have demonstrated that an OWC system using a broadband source (i.e. an LED) can be used not only for data transmission, but also for wireless power transmission. Moreover, the synchronization problem and the detection of level "1" or "0" of a bit often arise in the optical wireless communication systems. This is a result of the attenuation nature of the light over the distance and the problem of Non Line-Of-Sight (NLOS) between the emitter and the receiver. To deal with this problem, a communication protocol ensuring reliable digital data transmission with an adaptive bit level detection algorithm has been provided and its effectiveness has been demonstrated by the transmission of texts and images. In addition, this thesis provides a solution for the implementation of wavelength division multiplexed - orthogonal frequency division multiplexed (WDM-OFDM) transmitters based on the use of broadband sources in the infrared spectrum for centralized bidirectional fiber networks. Despite the chromatic dispersion that avoids the use of this type of optical sources, the inclusion of certain structures before detection allows the transmission of OFDM signals in optical links. Carrier reuse, dynamic bandwidth allocation and multiband OFDM signals transmission will be experimentally demonstrated by using optical broadband sources in WDM networks. The main results obtained during this thesis work demonstrate the study procedures, for each part, the effectiveness of the proposed solutions as well as the constraints encountered.<br>Sekkiou, I. (2021). Design of communication systems based on broadband sources for fiber and free space optical links [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/172542<br>TESIS

International Telemetering Conference Proceedings / October 25-28, 1993 / Riviera Hotel and Convention Center, Las Vegas, Nevada<br>With the advent of high-speed parallel-to-serial conversion interface standards reaching the 1.6 gigabit per second region, it is now possible to remote entire telemetry tracking systems over long distances without the need to maintain receivers, combiners, computers and antenna control units at the pedestal. In addition, it will soon be possible to digitize the RF signal(s) with high-speed flash-video analog-to-digital converters and transfer the data over these same links. This coupled with the improvements in fiber-optic L.E.D. and laser transmitters/ receivers and the constantly decreasing cost of fiber-optic cable, will allow for the eventual elimination of copper cabling for these interfaces. This will net a cost savings for the end user, provide for easier installations and increase the reliability of the overall system. This paper gives a brief history of the development of high-speed fiber-optic interface links, then expands into current interface standards and their utilization (such as MIL-STD-1553B, fiber data distributed interface (FDDI), HIPPI, etc.). Finally, a glimpse into the future of telemetry systems and the possibilities to soon be realized as major manufacturers of fiber-optic interfaces push well into the gigabit region. Topics include: • Replacement of existing copper cables between controller and pedestal using fiber-optic cable with interfaces that are not software-based intensive (black boxes); • Multiplexing pedestal control and status lines, RF feed commands, scan reference signals, and boresite video camera control; • Connecting and controlling multiple controllers and/or pedestals through one common interface cable; • Operating multiple tracking stations through one remote antenna controller; • Digitized RF telemetry signals sent along with pedestal, feed, video commands and status.

La présente étude concerne le domaine des systèmes de transmission par fibres optiques et plus particulièrement l’impact des différentes techniques de filtrage (optiques) sur les performances des systèmes de transmission optiques (métro, accès). En réception, ces systèmes présentent un filtre étroit, qui permet de filtrer le signal sans avoir à traiter le bruit dans la liaison. On considère généralement que l'étroitesse du filtre de réception est indispensable au bon fonctionnement d'une liaison sans répéteurs, et que la sensibilité de la liaison est d'autant plus grande que la largeur du filtre est proche de la limite théorique que constitue la largeur du spectre du signal émis. L'utilisation de tels filtres présente des contraintes. D'une part, les filtres présentent des pentes raides, et sont coûteux. D'autre part, un décalage de la longueur d'onde de l'émetteur est toujours possible, de sorte que la plupart des récepteurs comprennent des filtres de réception dont la longueur d'onde est asservie sur la longueur d'onde de l'émetteur. Pour un système de transmission à multiplexage en longueurs d'onde WDM, dans lequel plusieurs longueurs d'ondes distinctes peuvent être utilisées, ceci permet d’augmenter la capacité d’information transmise, mais pose cependant de réelles contraintes telle que la diaphonie entre voies. Les canaux sont multiplexés dans la même fibre puis filtrés à la réception par un filtre optique qui sert à la fois au démultiplexage des canaux et à un éventuel filtrage optique dans le spectre du canal étudié. Le filtre optique aura des paramètres variables : forme, bande passante, et longueur d’onde centrale, ensuite le canal ainsi filtré sera analysé par le récepteur. Ce dernier comprend une photodiode suivie d’un filtre électrique de la forme de la fonction de filtrage de type de Bessel d’ordre 5. La qualité de l’information sera évaluée, par le taux d’erreur binaire TEB. Dans ce travail de thèse nous proposons une analyse de l’impact des paramètres fondamentaux des filtres sur les performances d’une liaison par la simulation système<br>This study relates to the field of optical transmission systems fibers and more particularly the impact of different filtering techniques (optical) on the performance of optical transmission systems (metro access). Reception, these systems have a narrow filter, which filters the signal without having to deal with the noise in the link. It is generally considered that the narrowness of the receiving filter is indispensable for the proper functioning of a link without repeaters, and the sensitivity of the link is even greater than the width of the filter is close to the theoretical limit that is the spectrum width of the transmitted signal. The use of such filters has constraints. Firstly, the filters have steep slopes, and are expensive. On the other hand, a shift of the wavelength of the emitter length is always possible, so that most of the receivers comprise receiving filters whose wavelength is locked to the wavelength of the transmitter. For a transmission system with wavelength multiplexing, wherein plural different wavelengths may be used, this allows to increase the capacity of information transmitted, but however poses real constraints such that crosstalk between channels. The channels are multiplexed in the same fiber and filtered upon receipt by an optical filter which is used both in the channels and demultiplexing a possible optical filter in the spectrum of the considered channel. The optical filter has variable parameters: shape, bandwidth, and center wavelength, then the channel will be filtered and analyzed by the receiver. It includes a photodiode followed by an electrical filter of the form of the filter function of order Bessel type 5. Quality information will be evaluated by the bit error rate BER.In this thesis we propose to analyze the impact of the fundamental parameters of the filters on the performance of an optical system

Submitted by Valquíria Barbieri (kikibarbi@hotmail.com) on 2017-11-01T20:08:00Z No. of bitstreams: 1 DISS_2012_Danilo Costa Bertoloto.pdf: 8430681 bytes, checksum: 18a9ced8f731a2447eed45c8e94c3954 (MD5)<br>Approved for entry into archive by Jordan (jordanbiblio@gmail.com) on 2017-12-15T14:56:18Z (GMT) No. of bitstreams: 1 DISS_2012_Danilo Costa Bertoloto.pdf: 8430681 bytes, checksum: 18a9ced8f731a2447eed45c8e94c3954 (MD5)<br>Made available in DSpace on 2017-12-15T14:56:18Z (GMT). No. of bitstreams: 1 DISS_2012_Danilo Costa Bertoloto.pdf: 8430681 bytes, checksum: 18a9ced8f731a2447eed45c8e94c3954 (MD5) Previous issue date: 2012-08-30<br>Esta dissertação de caráter descritivo e exploratório busca traçar um panorama do nível de conexão que o Brasil, mais precisamente a Cidade de Cuiabá, capital do estado de Mato Grosso, está inserida. Busca-se apresentar, também, como se dão as conexões e quais backbones fazem parte da malha óptica que liga a cidade aos grandes centros e como estes se interligam com o mundo. O interesse principal da presente pesquisa é entender como Cuiabá, sede da Copa do Mundo de Futebol de 2014 se comportará como produtora, gestora e vendedora de informação, e se a conexão citada acima suportará essa demanda de tráfego. Busca-se então, levantar dados do mega-evento Copa do Mundo de futebol de 2010 para se apontar a demanda de infra-estrutura de comunicação baseada em fibra óptica para a Copa de 2014 no Brasil, Cuiabá.<br>This dissertation was a descriptive and exploratory search to give an overview of the level of connection that Brazil, more precisely the city of Cuiabá, capital of Mato Grosso, is inserted. Search is also present, as it gives the connections and backbones which are part of the optical network that connects the city to major centers and how they interrelate with the world. However, the ultimate concern of this research is to understand how to Cuiabá, the headquarters of the Football World Cup 2014, will behave as a producer, manager and seller information, and the connection to the above mentioned support the traffic demand. The aim is then to collect data from mega-event World Cup 2010 soccer pointing to the demand for communication infrastructure based on optical fiber for the 2014 World Cup in Brazil, Cuiabá.

För att uppnå ett långsiktigt hållbart samhälle krävs ekologisk, ekonomisk och social hållbar utveckling. Ett sätt att uppnå hållbarhet är genom digitalisering, men detta förutsätter att det finns robust och framtidssäker infrastruktur. Detta examensarbete syftar till att bidra med ökad kunskap om de möjligheter som kan skapas med hjälp av höghastighetsbredband genom fiber, samt att påvisa hur fiberutbyggnaden kan bidra till en hållbar utveckling. Genom att besvara de tre frågeställningarna ”Vilka möjligheter skapar höghastighetsbredband genom fiber?”, ”Vilka utmaningar finns för fiberutbyggnaden?” och ”Hur ska Sveriges kommuner arbeta för att underlätta fiberutbyggnaden och bidra till ett hållbart samhällsbyggande?” är målet att utreda olika lösningar för att uppnå hållbar samhällsplanering och samhällsbyggande genom digitalisering. De metoder som har valts för att framställa denna rapport är litteraturstudier, intervjuer, mailkontakt och möten med ett antal olika personer med olika positioner och roller inom offentlig sektor. Största delen av rapportens innehåll baseras på litteraturstudier från Sverige. Andra metoder som har tillämpats kompletterar litteraturstudien. Resultaten visade att höghastighetsbredband skapar nya möjligheter och bättre förutsättningar för vård och omsorg, utbildning, ökad tillväxt, minskad klimatpåverkan samt ekonomiska besparingar för privatpersoner och näringsverksamhet. Av resultaten framkom även att det finns ett antal faktorer som kan hindra utvecklingen av en effektiv utbyggnad av höghastighetsbredband. En utmaning är att skapa gemensam och enhetlig tillståndsprocess för marktillträde i Sveriges olika kommuner med olika geografiska skillnader och olika förutsättningar. En annan utmaning är att det saknas tillräcklig samverkan och samordning mellan olika offentliga myndigheter. Ökad samordning mellan olika interna funktioner, samt i vilken grad offentliga myndigheter samplanerar infrastrukturarbeten är viktiga delar för att lösa dessa utmaningar. Vidare är implementering av digitala system för hantering av kommunala tillståndsprocesser en effektiv lösning för att främja en hållbar samhällsutveckling. Slutsatsen av arbetet är att dagens och framtidens samhälle är beroende av välfungerande IT-infrastruktur. Det finns många hinder och utmaningar på vägen som måste lösas innan en hållbar samhällsutveckling kan uppnås. Med rätt planering, strategiskt arbete och helhetstänk kan dessa utmaningar omvandlas till helt nya möjligheter.<br>In order to achieve a long-term sustainable society, it requires ecological, economic and socially sustainable development. One way of achieving sustainability is through digitization, but this requires robust and future-proof infrastructure. This thesis aims to contribute to increased knowledge about the possibilities that can be created by using high-speed broadband through the fiber, as well as demonstrating how the development of fiber can contribute to sustainable development. By answering the three research questions "What opportunities create high-speed bandwidth through fiber?", "What challenges are there for fiber expansion?" and "How will Sweden's municipalities work to facilitate the fiber expansion and contribute to sustainable community building?" the goal is to investigate different solutions for achieving sustainable social planning and community building through digitization. The methods chosen to meet the objectives are literature studies, interviews, mail contacts and meetings with a number of different people with different positions and roles in the public sector. The majority of this report's content is based on literature studies from Sweden. Other methods that have been applied complement the literature study. The results showed that high-speed broadband creates new opportunities and better conditions for care and education, increased growth, reduced climate impact and economic savings for individuals and business. The results also revealed that there are a number of factors that could hinder the development of an efficient expansion of high-speed broadband. One challenge is to create a common and unified permission process for land access in Sweden's different municipalities, with different geographic differences and different conditions. Another challenge is that there are insufficient cooperation and coordination between different public authorities. By increasing coordination between various internal functions, as well as the extent to which public authorities jointly plan the infrastructure work is key components in addressing these challenges. Furthermore, implementation of digital systems for managing municipal permission processes is an effective solution for promoting sustainable social development. The conclusion of this thesis is that today's and tomorrow's society is dependent on well-functioning IT-infrastructure. There are many obstacles and challenges that must be solved before sustainable development can be achieved. With proper planning, strategic work, and a holistic thinking these challenges can be transformed into new possibilities.

碩士<br>國立中山大學<br>海下技術研究所<br>86<br>This thesis includes two parts: the broadband erbium-doped superfluorescent fiber source (SFS) for fiber optic gyroscope (FOG), and the fiber-optic video transmission technique of remotely operated vehicle (ROV). For the study of SFS for FOG, we investigate and compare the characteristics of erbium-doped SFS using different flattening techniques in double-pass forward (DPF) and double-pass backward (DPB) configurations. The intrinsic flattening is to optimize the erbium-doped fiber (EDF) length and pump power for an SFS to obtain high output power, wide line-width, and stable mean wavelength. The extrinsic flattening methods include addition of an appropriate length of the samarium-doped fiber (SDF) or by adding a short-period fiber Bragg grating (FBG) notch filter at the output port of the SFS. Experimental results show that both DPF and DPB SFS's have similar features in output power, line-width, and mean wavelength stability for each of the flattening methods. Although the DPF and DPB SFS's with the intrinsic flattening technique have a larger output power, they accompanied with large spectral power variation. The DPF and DPB SFS's with short-period FBG notch filter can achieve a wider line-width with excellent spectral flatness and better mean wavelength stability. To the best of our knowledge, both the FBG-flattened DPF and DPB SFS's are the most flat, broadband erbium-doped SFS's ever reported. On the contrary, both DPF and DPB SFS's using the SDF as a spectral flattener have no benefits in all characteristics. For the study of fiber-optic video transmission technique for ROV, we have investigated the feasibility of both wavelength division multiplexing (WDM) and sub-carrier multiplexing (SCM) techniques for ROV fiber-optic transmission system. Both techniques can reduce the required fiber counts, and thus decrease the outside diameter of the used optical fiber cable. Furthermore, simplify the rotary fiber-optic connector. In consequence, both techniques not only lower down the system cost of ROV, and make the operation of winches more easily, but also offer the expandability of fiber-optic communication system. For the SCM technique, the number of required optical transmitters and receivers can be reduced again as compared with the WDM one.

碩士<br>國立中央大學<br>電機工程研究所<br>95<br>In all access networks, optical fiber plays an imperative role. Fiber carries multimedia signals such as video, audio and data with a combination of subcarrier multiplexed radio over fiber and digital baseband formats. Therefore, radio over fiber plays key role in both wired and wireless broadband multimedia access networks. In this thesis, a simultaneous modulation and fiber-optic transmission of 1.25Gb/s digital signal and 2.4GHz RF signal with Gaussian minimum shift keying(GMSK) data is investigated. We compare two demodulation schemes which demodulate single digital signal and multiple radio channels in optical and electrical domain. In addition, we also compare two combination schemes which combine single digital signal and multiple radio channels in optical and electrical domain. The optimum operating conditions for digital signal and multiple radio channels are also investigated.

碩士<br>國立交通大學<br>光電工程系所<br>93<br>The demand on both wired and wireless access network is accelerating. For wireless access, one feasible option is radio over fiber (Rof). There is an emerging need to merge the fixed wired network and the RoF network for low cost infrastructure. So, in this thesis, several fiber-optic links that support simultaneous transmission of baseband data and radio signals are presented. By using simulation tool, VPI, we demonstrate two novel modulation methods which load 60-GHz-band radio signals on the frequency shift keying (FSK) and differential phase shift keying (DPSK) modulated 10Gbps baseband data, respectively. Moreover, two schemes which combine 20-GHz-band radio signals and 2.488Gbps baseband data in electrical and optical domain are compared through simulation and experimental results. These architectures are expected to be useful in the fields of fiber communication systems.