Ultra-long range Brillouin Optical Time Domain Analysis

Nuestro estilo de vida actual, basado en la industrialización y el consumo, requiere de grandes infraestructuras que puedan dar servicio a todas las necesidades asociadas al entorno: autopistas, líneas ferroviarias de alta velocidad, presas, gasoductos, oleoductos, estaciones de aerogeneración, líneas de alta tensión, etc. Evidentemente, la seguridad de las citadas estructuras es una prioridad ya que decenas, cientos, e incluso miles de vidas pueden estar en riesgo en caso de accidente. Ese creciente requisito en términos de seguridad, está aumentando de manera considerable el desarrollo y aplicación de sensores de fibra óptica en detrimento de los típicos sensores eléctricos. Este reemplazo se debe a ciertas ventajas que tienen los dispositivos basado en fibra óptica: pequeño tamaño y ligereza, menor coste, baja atenuación, capacidad de multiplexación, inmunidad al ruido electromagnético o resistencia a temperaturas extremas. Evidentemente, no todos los sensores de fibra óptica son aplicables a cualquier tipo de estructura o aplicación. En el campo de las grandes infraestructuras (> 25-30 km), los sistemas de fibra basados en la tecnología BOTDA (Brillouin Optical Time Domain Analysis) están tomando cada vez mayor protagonismo debido a sus cualidades en rango de medida (> 50 km) y resolución ( 100 km), donde la fibra tenga que ir y volver a la estación de sensado (> 200 km) sin posibilidad de que la luz sea amplificada por algún elemento intermedio. Además, cada vez se demanda más la posibilidad de monitorizar grandes estructuras (> 100 km) con resoluciones por debajo del metro, lo que dificulta considerablemente la implementación de los sistemas BOTDA. En este trabajo de tesis, se desarrolla un estudio cuidadoso de todos los problemas asociados al incremento de distancia y resolución en sistemas BOTDA y, consecuentemente, se proponen técnicas aplicables para evitarlos. En particular, abordaremos en profundidad los desafíos y las constantes de diseño de los sistemas BOTDA asistidos por Raman. La amplificación Raman en sistemas BOTDA implica un aumento del rango de sensado pero, desgraciadamente, introduce un ruido en la señal detectada denominado RIN (Relative Intensity Noise). Para evitar los problemas asociados a la transferencia de RIN, propondremos diferentes métodos capaces de eliminar parcialmente las características típicas del ruido RIN. Gracias a la aplicación de estas nuevas técnicas y procedimientos de optimización, se demuestra de manera experimental el sensado a lo largo de 100 km con 0,5 metros de resolución y, por primera vez, una medición lineal de 240 km de fibra (120 km de fibra sensible) con una resolución de 5 metros

Self-heterodyne detection for SNR improvement and distributed phase-shift measurements in BOTDA

In this paper we present a Brillouin optical time domain analysis (BOTDA) sensor that takes advantage of the enhanced characteristics obtained employing self heterodyne optical detection combined with synchronous demodulation. By employing this technique we increase the sensitivity of the sensor and demonstrate experimentally a 12.35 dB enhancement in the SNR compared to conventional direct-detection systems. This detection scheme also enables distributed measurements of the Brillouin phase shift in an optical fiber, which can lead to enhanced BOTDA schemes

Design and fabrication of customized fiber gratings to improve the interrogation of optical fiber sensors

[EN] Fiber grating sensors and devices have demonstrated outstanding capabilities in both telecommunications and sensing areas, due to their well-known advantageous characteristics. Therefore, one of the most important motivations lies in the potential of customized fiber gratings to be suitably employed for improving the interrogation process of optical fiber sensors and systems. This Ph.D. dissertation is focused on the study, design, fabrication and performance evaluation of customized fiber Bragg gratings (FBGs) and long period gratings (LPGs) with the double aim to present novel sensing technologies and to enhance the response of existing sensing systems. In this context, a technique based on time-frequency domain analysis has been studied and applied to interrogate different kind of FBGs-based sensors. The distribution of the central wavelength along the sensing structures has been demonstrated, based on a combination of frequency scanning of the interrogating optical pulse and optical time-domain reflectometry (OTDR), allowing the detection of spot events with good performance in terms of measurand resolution. Moreover, different customized FBGs have been interrogated using a technology inspired on the operation principle of microwave photonics (MWP) filters, enabling the detection of spot events using radio-frequency (RF) devices with modest bandwidth. The sensing capability of these technological platforms has been fruitfully employed for implementing a large scale quasi-distributed sensor, based on an array of cascaded FBGs. The potentiality of LPGs as fiber optic sensors has also been investigated in a new fashion, exploiting the potentials of MWP filtering techniques. Besides, a novel approach for simultaneous measurements based on a half-coated LPG has been proposed and demonstrated. Finally, the feasibility of FBGs as selective wavelength filters has been exploited in sensing applications; an alternative approach to improve the response and performance of Brillouin distributed fiber sensors has been studied and validated via experiments. The performance of the reported sensing platforms have been analyzed and evaluated so as to characterize their impact on the fiber sensing field and to ultimately identify the use of the most suitable technology depending on the processing task to be carried out and on the final goal to reach.[ES] Los sensores y dispositivos en fibra basados en redes de difracción han mostrado excepcionales capacidades en el ámbito de las telecomunicaciones y del sensado, gracias a sus excelentes propiedades. Entre las motivaciones más estimulantes destaca la posibilidad de fabricar redes de difracción ad-hoc para implementar y/o mejorar las prestaciones de los sensores fotónicos. Esta tesis doctoral se ha enfocado en el estudio, diseño, fabricación y evaluación de las prestaciones de redes de difracción de Bragg (FBGs) y de redes de difracción de periodo largo (LPGs) personalizadas con el fin de desarrollar nuevas plataformas de detección y a la vez mejorar la respuesta y las prestaciones de los sensores fotónicos ya existentes. En este contexto, una técnica basada en el análisis tiempofrecuencia se ha estudiado e implementado para la interrogación de sensores en fibra basados en varios tipos y modelos de FBGs. Se ha analizado la distribución de la longitud de onda central a lo largo de la estructura de sensado, gracias a una metodología que conlleva el escaneo en frecuencia del pulso óptico incidente y la técnica conocida como reflectometria óptica en el dominio del tiempo (OTDR). De esta manera se ha llevado a cabo la detección de eventos puntuales, alcanzando muy buenas prestaciones en términos de resolución de la magnitud a medir. Además, se han interrogado varias FBGs a través de una técnica basada en el principio de operación de los filtros de fotónica de microondas (MWP), logrando así la detección de eventos puntuales usando dispositivos de radio-frecuencia (RF) caracterizados por un moderado ancho de banda. La capacidad de sensado de estas plataformas tecnológicas ha sido aprovechada para la realización de un sensor quasi-distribuido de gran alcance, formado por una estructura en cascada de muchas FBGs. Por otro lado, se han puesto a prueba las capacidades de las LPGs como sensores ópticos según un enfoque novedoso; para ello se han aprovechados las potencialidades de los filtros de MWP. Asimismo, se ha estudiado y demostrado un nuevo método para medidas simultáneas de dos parámetros, basado en una LPG parcialmente recubierta por una película polimérica. Finalmente, se ha explotado la viabilidad de las FBGs en cuanto al filtrado selectivo en longitud de onda para aplicaciones de sensado; para ello se ha propuesto un sistema alternativo para la mejora de la respuesta y de las prestaciones de sensores ópticos distribuidos basados en el scattering de Brillouin. En conclusión, se han analizado y evaluado las prestaciones de las plataformas de sensado propuestas para caracterizar su impacto en el ámbito de los sistemas de detección por fibra y además identificar el uso de la tecnología más adecuada dependiendo de la tarea a desarrollar y del objetivo a alcanzar.[CA] Els sensors i dispositius en fibra basats en xarxes de difracció han mostrat excepcionals capacitats en l'àmbit de les telecomunicacions i del sensat, gràcies a les seus excel¿lents propietats. Entre les motivacions més estimulants destaca la possibilitat de fabricar xarxes de difracció ad-hoc per a implementar i/o millorar les prestacions de sensors fotònics. Esta tesi doctoral s'ha enfocat en l'estudi, disseny, fabricació i avaluació de les prestacions de xarxes de difracció de Bragg (FBGs) i de xarxes de difracció de període llarg (LPGs) personalitzades per tal de desenvolupar noves plataformes de detecció i al mateix temps millorar la resposta i les prestacions dels sensors fotònics ja existents. En este context, una tècnica basada en l'anàlisi temps-freqüència s'ha estudiat i implementat per a la interrogació de sensors en fibra basats en diversos tipus i models de FBGs. S'ha analitzat la distribució de la longitud d'ona central al llarg de l'estructura de sensat, gràcies a una metodologia que comporta l'escaneig en freqüència del pols òptic incident i la tècnica coneguda com reflectometria òptica en el domini del temps (OTDR). D'esta manera s'ha dut a terme la detecció d'esdeveniments puntuals, aconseguint molt bones prestacions en termes de resolució de la magnitud a mesurar. A més, s'han interrogat diverses FBGs a través d'una tècnica basada en el principi d'operació dels filtres de fotònica de microones (MWP), aconseguint així la detecció d'esdeveniments puntuals utilitzant dispositius de ràdio-freqüència (RF) caracteritzats per un moderat ample de banda. La capacitat de sensat d'aquestes plataformes tecnològiques ha sigut aprofitada per a la realització d'un sensor quasi-distribuït a llarga escala, format per una estructura en cascada de moltes FBGs. D'altra banda, s'han posat a prova les capacitats de les LPGs com a sensors òptics segons un enfocament nou; per a això s'han aprofitat les potencialitats dels filtres de MWP. Així mateix, s'ha estudiat i demostrat un nou mètode per a mesures simultànies de dos paràmetres, basat en una LPG parcialment recoberta per una pel¿lícula polimèrica. Finalment, s'ha explotat la viabilitat de les FBGs pel que fa al filtrat selectiu en longitud d'ona per a aplicacions de sensat; per això s'ha proposat un sistema alternatiu per a la millora de la resposta i de les prestacions de sensors òptics distribuïts basats en el scattering de Brillouin. S'han analitzat i avaluat les prestacions de les plataformes de sensat propostes per a caracteritzar el seu impacte en l'àmbit dels sistemes de detecció per fibra i a més identificar l'ús de la tecnologia més adequada depenent de la tasca a desenvolupar i de l'objectiu a assolir.Ricchiuti, AL. (2016). Design and fabrication of customized fiber gratings to improve the interrogation of optical fiber sensors [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/66343TESISPremiad

Management of fiber physical effects in high-speed optical communication and sensor systems

Ph.DDOCTOR OF PHILOSOPH

Novel Specialty Optical Fibers and Applications

Novel Specialty Optical Fibers and Applications focuses on the latest developments in specialty fiber technology and its applications. The aim of this reprint is to provide an overview of specialty optical fibers in terms of their technological developments and applications. Contributions include:1. Specialty fibers composed of special materials for new functionalities and applications in new spectral windows.2. Hollow-core fiber-based applications.3. Functionalized fibers.4. Structurally engineered fibers.5. Specialty fibers for distributed fiber sensors.6. Specialty fibers for communications

Advanced trends in nonlinear optics applied to distributed optical-fibre sensors

The distributed optical-fibre sensors based on the properties of Brillouin scattering is the central object of this thesis. In the past decade, optical fibres have gained a large interest as sensors: attractive solutions based on the non-linear stimulated Brillouin scattering have been proposed in the early 90s and the possibility to achieve long-range fully distributed strain measurements has been extensively demonstrated. The Brillouin interaction is responsible for the coupling between two optical waves and an acoustic wave when a resonance condition is fulfilled. Since the resonance condition is strain and temperaturedependent, by determining the resonance frequency we directly get a measure of temperature or strain. Local information about the acousto-optical resonance condition is typically obtained by using pulsed lightwaves and a classical time-of-flight technique (BOTDA technique). The main goal of this work has been the development of an innovative technique for the generation of optical signals, using a set of locked lasers – instead of the traditional techniques using external modulators. The utilisation of the injection-locking of semiconductor lasers is the key of the entire set-up and represents an entirely new and original approach, since it brings significant improvements in terms of SNR and costs. As long as intense pulses propagate along the fibre, the optical signals can be seriously degraded by several nonlinear interactions occurring inside the fibre; we show that the nonlinear effect exhibiting the lowest threshold power is the modulation instability (MI) process. From the study of the dynamic behaviour of MI we could observe the Fermi-Pasta-Ulam (FPU) recurrence over few periods in very comfortable conditions. One original application of Brillouin sensing has been the dosimetric measurement of ionising radiations in a nuclear environment. The measurement campaign has not only shown that distributed sensors based on Brillouin spectral analysis are radiation tolerant up to very high doses, but has also revealed the first observation – to our knowledge – of the negative compaction of silica in fibres. Distributed fibre sensors based on stimulated Brillouin scattering offer a unique capability for the analysis of optical signals and nonlinear phenomena in optical fibres. We present a generalised theoretical approach to the problem of localised sensing and report on the first distributed measurement – to our knowledge – of the parametric gain in a single-pump fibre-optics parametric amplifier (FOPA)

Stimulated Brillouin scattering based optical signal processing for fiber-optic communications and sensing.

基於光纖非線性效應的光學信號處理在光纖通信和傳感中起著重要作用。在各種非線性效應中，光纖中的布里淵散射不僅被廣泛應用於高速通信信號的處理，而且被用於建立光纖傳感器。本文研究基於布里淵散射的光學信號處理新技術在光通信和傳感中的應用。近年來由於慢光技術在實現時間延遲和光學信號處理中的廣泛應用，它吸引了廣泛的注意力。 在各種實現慢光的技術中，基於布里淵散射的慢光技術展示了很大的潛力，因為它具有在常溫工作以及與現有光纖系統兼容的優勢。但是由於布里淵泵浦和信號之間嚴格的頻率要求，大多數的研究工作是建立於一個泵浦延遲一個信號的基礎上，所以只能獲得一個被延遲的信道。本文提出了一種在一個布里淵泵浦的慢光系統中實現同時產生多個延遲信號的技術。這種技術應用了基於四波混頻的廣播效應。輸入信號被布里淵泵浦延遲的同時，延遲通過三個四波混頻泵浦的廣播效應傳遞給其他六個新產生的信道。這種慢光廣播技術可以被應用於並行光學信號處理，比如實現多信道同步以及時分複用。光纖傳感技術為結構的健康提供了一種優秀的監測方法，尤其是溫度和應力的監測。在過去的二十年間，基於布里淵散射的傳感技術吸引了大批人的興趣，因為布里淵光纖傳感器擁有高分辨率，長距離監測以及監測範圍廣的優點。本文提出了一種新的基於布里淵慢光的溫度和應力傳感技術。布里淵頻移的溫度和應力相關性使得輸入光脉衝的延遲也與溫度和應力相關，因此我們通過測量這個延遲來監測溫度和應力。我們分別實現了對100米和2米單模光纖的溫度測量。隨後我們也實現了分佈式溫度和應力監測。通過設置泵浦和探測光脉衝之間的延遲時間，我們可以監測特定位置的光纖。因此，通過控制整個延遲時間，我們實現了對整個光纖的溫度和應力分佈的監測。相比于普通的布里淵光纖傳感器，我們這種技術擁有以下優點：更加直接簡單的實現監測，快速的反應時間以及實時監測的潛力。波長轉換在路由和交換中起了很重要的作用。在各種波長轉換的技術中，基於四波混頻的波長轉換非常優越因為它具有對調製格式，比特率以及通信協議透明的優點。但是，四波混頻只有在各個光波的相速度匹配的情況下才能有效的產生。這種匹配條件很難在一個很寬的頻段內保持，因此四波混頻的轉換帶寬是很有限的。本文提出了一種基於零增益受激布里淵散射的方法來動態地控制四波混頻的相位匹配。 通過布里淵泵浦和斯托克斯光引入自我補償的受激布里淵增益和損耗，四波混頻的相位匹配條件可以被受激布里淵散射激發的折射率改變來靈活的控制，並且不會影響四波混頻初始的參數。我們把這種零增益受激布里淵散射應用于增大簡並四波混頻的帶寬，增強通信信息波長轉換的效果，全光調控非簡並四波混頻的帶寬，實現偏振不敏感寬帶波長轉換以及延長基於四波混頻波長轉換和色散的延遲線的最大延遲時間。低噪聲寬帶放大可以通過光學參量過程來實現。雖然光參量放大器可以提供高至70分貝的增益，但是這種參量放大器經常受限於各個光波的相位不匹配。在本文中，我們把零增益受激布里淵散射用於光參量放大器來動態的控制它的增益譜。基於這種技術，我們動態地改變了傳統的“M“型增益譜，並且由此得到了非常平滑的增益譜，增益的變換量僅僅在0.1分貝以內。Optical signal processing based on fiber nonlinearities plays an important role in both fiber-optic communications and sensing. Among various nonlinear effects, stimulated Brillouin scattering (SBS) in optical fibers has been widely employed not only in processing of high-speed communication signals, but also in constructing fiber-optic sensors. This thesis investigates new techniques of optical signal processing based on SBS for fiber-optic communications and sensing.In the recent years, slow light has attracted considerable interest because of its numerous applications, in realizing variable true time delay and in optical information processing. Among various slow light mechanisms, the SBS based slow light shows great potential in all-optical signal processing due to the advantages of room-temperature operation and device compatibility with existing fiber systems. However, owing to the tight requirement of spectral alignment between the SBS pump and the signal, most of the published works are for the case where one SBS pump is used to delay a single channel. Hence, only one delayed channel is obtained. In this thesis, we demonstrate a technique to simultaneously generate multiple delayed signals through four-wave mixing (FWM) wavelength multicasting in a single-pump stimulated Brillouin scattering (SBS) based slow light system. The signal delay is achieved with a SBS pump while at the same time the delay is transferred to six other channels by three FWM pumps employed for wavelength multicasting. This slow light multicasting technique may find applications in parallel optical information processing such as simultaneous multichannel synchronization and time division multiplexing.Fiber-optic sensor techniques provide a promising approach for structure health monitoring, especially the temperature and strain monitoring. The technique based on Brillouin scattering has attracted much interest in the past two decades because Brillouin fiber sensors offer advantages of high resolution, long distance sensing, and large sensing range. In the thesis, we propose and experimentally demonstrate a new method for temperature/strain sensing using stimulated Brillouin scattering based slow light. The approach relies on temperature/strain dependence of the Brillouin frequency shift in a fiber, hence the time delay of an input probe pulse. By measuring the delay, temperature/strain sensing can be realized. We achieve temperature measurement for both a 100 m single mode fiber (SMF) and a 2 m SMF. Distributed temperature/strain sensing has been demonstrated later. The temperature/strain of a particular fiber section can be monitored by setting an appropriate relative delay between the pump and probe pulses. By controlling the relative delay, we have achieved distributed profiling of the temperature/strain along the whole sensing fiber. Compared to conventional Brillouin fiber sensors, our scheme has the merits of more straightforward implementation, fast response and potential of real-time monitoring.Wavelength conversion plays an important role in wavelength routing and switching. Among various schemes for wavelength conversion, the one based on FWM is superior as it offers advantages in being transparent to modulation formats, bit-rates, and communication protocols. However, significant FWM can occur only if the phase velocities of the interplaying waves are matched. The matching condition can hardly be satisfied over a wide spectral range and hence the conversion bandwidth is often limited. In this thesis, we propose and experimentally demonstrate an approach to dynamically control the FWM phase matching condition by using gain-transparent SBS. By introducing self-compensation of optical gain/loss with SBS pump and Stokes waves, the FWM phase matching condition can be flexibly controlled through SBS induced refractive index change without affecting the initial parameters of the FWM. The gain-transparent scheme is employed to enlarge the degenerate FWM conversion bandwidth, enhance the performance in wavelength conversion of communication signals, all-optically manipulate non-degenerate FWM conversion bandwidth, achieve both polarization-insensitive and wideband operation in a dual orthogonal pump wavelength converter, and extend the maximum optical delay of a delay line based on FWM wavelength conversion and dispersion.Low noise and broadband amplification are possible by using optical parametric processes. Although fiber-optic parametric amplifier (FOPA) can provide gain as high as 70 dB, its operation is often confined by phase mismatch of the interplaying fields. In this thesis, we apply gain-transparent SBS to a FOPA and dynamically control its gain profile. The conventional “M“ shape gain profile can be dynamically changed. Flattening of the gain profile to within 0.1 dB variation has been achieved.Detailed summary in vernacular field only.Detailed summary in vernacular field only.Detailed summary in vernacular field only.Detailed summary in vernacular field only.Detailed summary in vernacular field only.Wang, Liang.Thesis (Ph.D.)--Chinese University of Hong Kong, 2013.Includes bibliographical references.Abstract also in Chinese.ABSTRACT --- p.iACKNOWLEDGEMENT --- p.viTABLE OF CONTENT --- p.viiiChapter 1 --- INTRODUCTION --- p.1Chapter 1.1 --- Overview of Optical Signal Processing --- p.3Chapter 1.2 --- Outline of the Thesis --- p.6References --- p.10Chapter 2 --- STIMULATED BRILLOUIN SCATTERING IN OPTICAL FIBERS --- p.15Chapter 2.1 --- Physical Process of Brillouin Scattering --- p.16Chapter 2.2 --- Stimulated Brillouin Scattering Under Steady-State Conditions --- p.19Chapter 2.3 --- The Brillouin Gain --- p.22Chapter 2.3.1 --- Complex Brillouin Gain --- p.22Chapter 2.3.2 --- Brillouin Gain Spectrum --- p.24Chapter 2.4 --- Threshold of Brillouin Scattering --- p.30References --- p.32Chapter 3 --- SLOW LIGHT BASED ON SBS IN OPTICAL FIBERS --- p.34Chapter 3.1 --- Introduction to Slow Light --- p.35Chapter 3.2 --- Slow Light based on SBS in Optical Fibers --- p.39Chapter 3.2.1 --- Mathematical Description --- p.39Chapter 3.2.2 --- Delay of Optical Signals by SBS based Slow Light --- p.42Chapter 3.3 --- Generation of Multichannel Delayed Pulses by FWM Assisted SBS Slow Light System --- p.46Chapter 3.3.1 --- Principle and Experimental Setup --- p.47Chapter 3.3.2 --- Results and Discussion --- p.51References --- p.58Chapter 4 --- SBS SLOW-LIGHT-BASED FIBER-OPTIC SENSOR --- p.64Chapter 4.1 --- Introduction to Fiber-Optic Sensors --- p.66Chapter 4.2 --- Principle of Fiber-Optic Sensor based on SBS Slow Light --- p.69Chapter 4.3 --- Temperature Sensing by SBS Slow Light for a Whole Segment of Fiber --- p.73Chapter 4.3.1 --- Temperature Sensing for a 100 m Single-Mode Fiber --- p.73Chapter 4.3.2 --- Temperature Sensing for a 2 m Single-Mode Fiber --- p.76Chapter References --- p.80Chapter 5 --- DISTRIBUTED TEMPERATURE & STRAIN SENSING USING SBS-BASED SLOW LIGHT --- p.82Chapter 5.1 --- Introduction to Distributed Brillouin Fiber Sensor --- p.84Chapter 5.2 --- Distributed Fiber-Optic Temperature Sensor Using SBS-based Slow Light --- p.91Chapter 5.2.1 --- Principle and Experimental Setup --- p.92Chapter 5.2.2 --- Results and Discussion --- p.94Chapter 5.3 --- Distributed Fiber-Optic Strain Sensor Using SBS-based Slow Light --- p.101Chapter 5.3.1 --- Principle and Experimental Setup --- p.101Chapter 5.3.2 --- Results and Discussion --- p.104References --- p.109Chapter 6 --- DYNAMIC CONTROL OF PHASE MATCHING IN FWM WAVELENGTH CONVERSION BY GAIN-TRANSPARENT SBS --- p.114Chapter 6.1 --- Phase-matching Condition in FWM --- p.116Chapter 6.2 --- Conversion Bandwidth Enlargement in Degenerate FWM Using Phase-Matching Control by Gain-Transparent SBS --- p.119Chapter 6.2.1 --- Principle and Experimental Setup --- p.120Chapter 6.2.2 --- Results and discussion --- p.125Chapter 6.3 --- Wavelength Conversion of Communication Signals Using Degenerate FWM with Gain-Transparent SBS for Phase-Matching Control --- p.131Chapter 6.3.1 --- Principle --- p.131Chapter 6.3.2 --- Wavelength Conversion for Amplitude-Modulated Signals --- p.133Chapter 6.3.3 --- Wavelength Conversion for Phase-Modulated Signals --- p.139Chapter 6.3.4 --- Discussion --- p.145Chapter 6.4 --- All-Optical Manipulation of Non-Degenerate FWM Conversion Bandwidth by Gain-Transparent SBS --- p.150Chapter 6.4.1 --- Principle and Experiment Setup --- p.151Chapter 6.4.2 --- Results and Discussion --- p.153Chapter 6.5 --- Enhanced Performance of Polarization-insensitive Wavelength Conversion through Dynamic Control of Optical Phase --- p.157Chapter 6.5.1 --- Principle and Experiment Setup --- p.157Chapter 6.5.2 --- Results and Discussion --- p.160Chapter 6.6 --- Extension of the Maximum Optical Delay using Gain-Transparent-SBS-Controlled FWM Wavelength Conversion and Group Velocity Dispersion --- p.165Chapter 6.6.1 --- Principle and Experiment Setup --- p.166Chapter 6.6.2 --- Results and Discussion --- p.169References --- p.174Chapter 7 --- DYNAMIC CONTROL OF GAIN PROFILE IN FIBER OPTICAL PARAMETRIC AMPLIFIER BY GAIN-TRANSPARENT SBS --- p.182Chapter 7.1 --- Introduction to FOPA --- p.184Chapter 7.2 --- Dynamic Gain Profile in FOPA Assisted by Gain-Transparent SBS --- p.187Chapter 7.2.1 --- Principle and Experimental Setup --- p.187Chapter 7.2.2 --- Results and Discussion --- p.190References --- p.196Chapter 8 --- THESIS SUMMARY AND FUTURE WORK --- p.200Chapter 8.1 --- Summary --- p.201Chapter 8.2 --- Future Work --- p.206References --- p.208APPENDICES --- p.iChapter Appendix A. --- List of Publications --- p.iChapter Appendix B. --- List of Figures --- p.i