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Céreyon, Arnaud. "Amplification Raman et nanostructures." Lyon 1, 2008. http://www.theses.fr/2008LYO10133.
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Calmes, Lonnie Kirkland. "Solid-state Raman image amplification." Diss., The University of Arizona, 1998. http://hdl.handle.net/10150/288920.
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Amplification of low-light-level optical images is important for extending the range of lidar systems that image and detect objects in the atmosphere and underwater. The use of range-gating to produce images of particular range bins is also important in minimizing the image degradation due to light that is scattered backward from aerosols, smoke, or water along the imaging path. For practical lidar systems that must be operated within sight of unprotected observers, eye safety is of the utmost importance. This dissertation describes a new type of eye-safe, range-gated lidar sensing element based on Solid-state Raman Image Amplification (SSRIA) in a solid-state optical crystal. SSRIA can amplify low-level images in the eye-safe infrared at 1.556 μm with gains up to 106 with the addition of only quantum-limited noise. The high gains from SSRIA can compensate for low quantum efficiency detectors and can reduce the need for detector cooling. The range-gate of SSRIA is controlled by the pulsewidth of the pump laser and can be as short as 30-100 cm, using pump pulses of 2-6.7 nsec FWHM. A rate equation theoretical model is derived to help in the design of short pulsed Raman lasers. A theoretical model for the quantum noise properties of SSRIA is presented. SSRIA results in higher SNR images throughout a broad range of incident light levels, in contrast to the increasing noise factor with reduced gain in image intensified CCD's. A theoretical framework for the optical resolution of SSRIA is presented and it is shown that SSRIA can produce higher resolution than ICCD's. SSRIA is also superior in rejecting unwanted sunlight background, further increasing image SNR. Lastly, SSRIA can be combined with optical pre-filtering to perform optical image processing functions such as high-pass filtering and automatic target detection/recognition. The application of this technology to underwater imaging, called Marine Raman Image Amplification (MARIA) is also discussed. MARIA operates at a wavelength of 563 nm, which passes most efficiently through coastal ocean waters. The imaging resolution of MARIA in the marine environment can be superior to images produced by laser line scan or standard range-gated imaging systems.
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Fludger, Christopher Ronald Stephen. "Raman amplification for broadband optical communications." Thesis, University of Cambridge, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.620474.
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Ellingham, Tim John. "Raman amplification and performance altering effects." Thesis, Aston University, 2006. http://publications.aston.ac.uk/8024/.
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This thesis presents an experimental investigation into several applications of the Raman scattering effect in communication optical fibres as well as how some of these applications can be modified to enhance the resulting performance. The majority of the work contained within is based on laboratory results using many commercially available components. The results can be divided into and presented in three main parts: Firstly, a novel application of a known effect is used to broaden Raman pump light in order to achieve a more continuous distribution of gain with respect to wavelength. Multiple experimental results are presented, all based around the prior spreading of the pump spectrum before being used in the desired transmission fibre. Gathered results show that a notable improvement can be obtained from applying such a technique along with the scope for further optimisation work. Secondly, an investigation into the interaction between the well known effect of Four Wave Mixing (FWM) and Raman scattering is provided. The work provides an introduction to the effect as well commenting on previous literature regarding the effect and its mitigation. In response to existing research experimental results are provided detailing some limitations of proposed schemes along with concepts of how further alleviation from the deleterious effects maybe obtained. Lastly, the distributed nature of the Raman gain process is explored. A novel technique on how a near constant distribution of gain can be employed is implemented practically. The application of distributed gain is then applied to the generation of optical pulses with special mathematical properties within a laboratory setting and finally the effect of pump noise upon distributed gain techniques is acknowledged.
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Ben-Dor, Adi. "Non-linear impacts of forward-raman-amplification. /." [Beer Sheva] : Ben Gurion University of the Negev, 2008. http://aranne5.lib.ad.bgu.ac.il/others/Ben-DorAdi.pdf.
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Neto, Berta Maria Barbosa. "Alternative techniques for Raman amplification in telecommunications." Doctoral thesis, Universidade de Aveiro, 2010. http://hdl.handle.net/10773/7526.
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Doutoramento em FísicaO presente trabalho centra-se no estudo dos amplificadores de Raman em fibra ótica e suas aplicações em sistemas modernos de comunicações óticas. Abordaram-se tópicos específicos como a simulação espacial do amplificador de Raman, a equalização e alargamento do ganho, o uso de abordagens híbridas de amplificação através da associação de amplificadores de Raman em fibra ótica com amplificadores de fibra dopada com Érbio (EDFA) e os efeitos transitórios no ganho dos amplificadores. As actividades realizadas basearam-se em modelos teóricos, sendo os resultados validados experimentalmente. De entre as contribuições mais importantes desta tese, destaca-se (i) o desenvolvimento de um simulador eficiente para amplificadores de Raman que suporta arquitecturas de bombeamento contraprogantes e bidirecionais num contexto com multiplexagem no comprimento de onda (WDM); (ii) a implementação de um algoritmo de alocação de sinais de bombeamento usando a combinação do algoritmo genético com o método de Nelder- Mead; (iii) a apreciação de soluções de amplificação híbridas por associação dos amplificadores de Raman com EDFA em cenários de redes óticas passivas, nomeadamente WDM/TDM-PON com extensão a região espectral C+L; e (iv) a avaliação e caracterização de fenómenos transitórios em amplificadores para tráfego em rajadas/pacotes óticos e consequente desenvolvimento de soluções de mitigação baseadas em técnicas de clamping ótico.
The present work is based on Raman Fiber Amplifiers and their applications in modern fiber communication systems. Specific topics were approached, namely the spatial simulation of Raman fiber amplifiers, the gain enlargement and equalization the use of hybrid amplification approaches by association of Raman amplifiers with Erbium doped fiber amplifiers (EDFA) and the transient effect on optical amplifiers gain. The work is based on theoretical models, being the obtained results validated experimentally. Among the main contributions, we remark: (i) the development of an efficient simulator for Raman fiber amplifiers that supports backward and bidirectional pumping architectures in a wavelength division multiplexing (WDM) context; (ii) the implementation of an algorithm to obtain enlargement and equalization of gain by allocation of pumps based on the association of the genetic algorithm with the Nelder-Mead method; (iii) the assessment of hybrid amplification solutions using Raman amplifiers and EDFA in the context of passive optical networks, namely WDM/TDM-PON with extension the C+L spectral bands; (iv) the assessment and characterization of transient effects on optical amplifiers with bursty/packeted traffic and the development of mitigation solutions based on optical clamping.
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FARIA, GIANCARLO VILELA DE. "A RAMAN AMPLIFICATION STUDY USING TUNABLE OPTICAL REFLECTOMETRY." PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2005. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=7734@1.
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PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRODiante do crescimento do interesse pelos amplificadores Raman faz-se necessário um estudo mais detalhado destes. Uma técnica tradicionalmente já utilizada para analise de atenuação em enlaces, a reflectometria óptica no domínio do tempo, é empregada de maneira inovadora neste trabalho para a observação da amplificação Raman distribuída. O objetivo principal deste trabalho não é a analise de amplificadores Raman, mas sim a apresentação desta técnica como nova ferramenta observação do ganho Raman distribuído em fibras ópticas.
Due to increased interest in Raman amplifiers, a more detailed study of them is required. A technique traditionally used for analysis of attenuation on optical links, time domain optical reflectometry, is used in an innovative way in this work for observation of distributed Raman amplification. The main objective of this work in not the analysis of Raman amplifiers, but the introduction of this technique as a new tool for the observation of distributed Raman gain in optical fibers.
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Tan, Mingming. "Raman fibre laser based amplification in coherent transmission systems." Thesis, Aston University, 2016. http://publications.aston.ac.uk/28899/.
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The thesis presents a detailed study of different Raman fibre laser (RFL) based amplification techniques and their applications in long-haul/unrepeatered coherent transmission systems. RFL based amplifications techniques were characterised from different aspects, including signal/noise power distributions, relative intensity noise (RIN), mode structures of induced Raman fibre lasers, and so on. It was found for the first time that RFL based amplification techniques could be divided into three categories in terms of the fibre laser regime, which were Fabry-Perot fibre laser with two FBGs, weak Fabry-Perot fibre laser with one FBG and very low reflection near the input, and random distributed feedback (DFB) fibre laser with one FBG. It was also found that lowering the reflection near the input could mitigate the RIN of the signal significantly, thanks to the reduced efficiency of the Stokes shift from the FW-propagated pump. In order to evaluate the transmission performance, different RFL based amplifiers were evaluated and optimised in long-haul coherent transmission systems. The results showed that Fabry-Perot fibre laser based amplifier with two FBGs gave >4.15 dB Q factor penalty using symmetrical bidirectional pumping, as the RIN of the signal was increased significantly. However, random distributed feedback fibre laser based amplifier with one FBG could mitigate the RIN of the signal, which enabled the use of bidirectional second order pumping and consequently give the best transmission performance up to 7915 km. Furthermore, using random DFB fibre laser based amplifier was proved to be effective to combat the nonlinear impairment, and the maximum reach was enhanced by >28% in mid-link single/dual band optical phase conjugator (OPC) transmission systems. In addition, unrepeatered transmission over >350 km fibre length using RFL based amplification technique were presented experimentally using DP-QPSK and DP-16QAM transmitter.
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Keïta, Kafing. "amplification Raman stimulée de signaux hyperfréquences sur porteuse optique." Phd thesis, Université Paris Sud - Paris XI, 2006. http://tel.archives-ouvertes.fr/tel-00091197.
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Ce travail vise à l'élaboration d'un système d'amplification faible bruit de signaux hyperfréquences sur porteuse optique. Nous avons mené une étude expérimentale de l'amplification Raman dans des fibres optiques monomodes à 1550nm. La configuration contra-propageante -la moins bruitée- permet d'atteindre des gains nets de plus de 25dB, elle s'est aussi montrée plus performante en termes de RIN (relative intensity noise) qu'un EDFA commercial. Une analyse théorique de l'amplification Raman a été conduite dans le domaine spectral afin de quantifier le transfert de RIN de la pompe vers le signal. L'analyse a montré une décroissance de ce transfert à hautes fréquences que l'on considère un laser de pompe monochromatique faiblement modulé ou, à l'opposé, pseudo-incohérent. Par contre, à basses fréquences, le laser de pompe monochromatique faiblement modulé apporte un excès de bruit qui n'est pas présent avec la pompe pseudo-incohérente. Ce type de source de pompe peut donc présenter un intérêt tout particulier pour le développement d'amplificateurs Raman faible bruit pour les liaisons opto-hyperfréquences. Une autre piste envisagée est la réduction du bruit d'émission spontanée amplifiée. Nous avons étudié les moyens à mettre en œuvre pour parvenir à diminuer ce bruit. L'utilisation de deux lasers de pompe de même puissance présentant un faible décalage spectral (devant la largeur de la transition Raman) doit permettre d'atteindre ce résultat. Les descriptions holographique, "optique non linéaire" ou quantique de la diffusion Raman bifréquence indiquent que pour une réduction effective du bruit d'émission spontanée, il faut que les deux pompes soient opposées en amplitude.
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Vieux, Gregory. "Broad-band linear Raman chirped pulse amplification in plasma." Thesis, University of Strathclyde, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.435149.
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Yang, Xue. "Raman amplification of ultra-short laser pulses in plasma." Thesis, University of Strathclyde, 2013. http://oleg.lib.strath.ac.uk:80/R/?func=dbin-jump-full&object_id=23192.
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This thesis presents the experimental investigation of Raman amplification of ultrashort laser pulses by a counter propagating chirped pump pulse through resonant excitation of a plasma density wave. Since plasma is a gain medium able to withstand very high intensities, this scheme is proposed as the basis of a new generation of laser amplifiers capable of replacing Chirped Pulse Amplification (CPA) systems, which are limited by the damage threshold of solid state gain media. In this experiment, both the pump and the probe beams are generated from a 30 TW Ti:Sapphire CPA laser system. The chirped pump pulse is 250 ps long and centered at 805 nm. The probe pulse, compressed to minimum 70 fs and then frequency downshifted before the interaction with the pump pulse in the plasma, contains maximum 1 mJ of energy on target. The plasma is generated by striking a high voltage discharge across a hydrogen gas filled capillary waveguide with the electron plasma density controlled around 1 x 10p18scmp-3s. In addition to a CCD camera and a spectrometer, a self-built Frequency-Resolved Optical Gating (FROG) system is employed as a real time detector to fully reconstruct the probe pulse amplitude and phase. The experiment is performed in two stages, firstly with low pump energies, about 400 mJ, allowing the verification of chirped pulse Raman amplification mechanisms in the linear regime. In these conditions the energy gain grows exponentially with the pump energy and increases with backing pressure. The theoretical predictions showing that the probe pulse duration should be preserved when using a chirped pump pulse are confirmed. Maximum energy gain is 450%. The second stage is implemented with pump energies up to 950 mJ. Initially the Raman process develops in the linear regime. With the amplification of the probe pulse, the amplification mechanism can transit to a nonlinear process. The highest energy gain is 650%. Obvious bandwidth broadening mainly on the high frequency side and gain saturation with either increasing pump or probe energy are observed. Assisted by 1D aPIC simulations, the transition from the Raman linear regime to the nonlinear regime is analysed.
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Lyachev, Andrey. "High gain ultra-short laser pulse raman amplification in plasma." Thesis, University of Strathclyde, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.486537.
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This thesis presents an experimental study of broad-band Raman chirped pulse amplification in plasma. Amplification. of a short seed pulse occurs through stimulated Raman backscattering in the presence ofa counter-propagating chirped pump pulse in a preformed plasma waveguide channel. 300 and 200 Jlm diameter, 40 rom long, hydrogen-filled capillary discharge waveguides have been investigated. The plasma channel has the dual purpose of guiding the laser pulses over distances of many Rayleigh lengths and acting· as the nonlinear medium for the Raman instability. Laser energy transmission through the plasma channel, in single mode propagation, is observed ~o be better than 80 % for the pulses with intensities up to 5.8 X 1014 W cm-2. The dependence of the gain on pump intensity and plasma density is experimentally studied and confirms theoretical predictions. It is shown that higher pump intensities inside the capillary can be realised using unmatched guiding due to periodic oscillations ofthe laser beam waist along the plasma channel. Amplification of the seed pulse in the linear regime is obtained when the frequency detuning between the seed and the pump matches th~ plasma frequency. Thus the frequency difference between the pump and gain peaks enables to estimate the plasma density, measured around 1018 cm-3. The high gain regime has been investigated showing that peak gains of over 1200 % can be routinely realised. A peak gain of almost 3000 % has 'been observed under optimal conditions with the highest densities and pump energies. Several diagnostic systems have been developed for simultaneous detection of the spectral and energy gain together with the duration of the seed. Ultrashort pulse high gl;lin amplification of 80 fs, 5 mJ pulse has been demonstrated, giving a peak value of 800% and energy gain of 40 % together with 40 % increase in pulse duration. Amplification ofthe whole seed pulse spectra has been demonstrated using an optical cut-off filter to provide a sufficient detul1ed seed pulse. Future increase of the efficiency will occur in the nonlinear regime of the stimulated Raman backscattering resulting in compression ofthe seed pulse.
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Farmer, John. "Numerical models for the simulation of Raman amplification in plasma." Thesis, University of Strathclyde, 2012. http://oleg.lib.strath.ac.uk:80/R/?func=dbin-jump-full&object_id=22721.
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Raman amplification in plasma is a potential method of producing ultra-short, ultra-intense laser pulses. As amplification in realistic systems involves many competing nonlinear processes, numerical simulations are often used to better understand the associated complex behaviour. Different models offer different advantages and limitations. This work presents a study of three distinct numerical models: a particle-in-cell (PIC) code, a threewave model derived from a fluid treatment of plasma, and the envelope-PIC code aPIC. PIC codes are known to incur large computational overheads. A new numerical instability associated with nonlinear plasma waves has been identified, which can result in a significant increase in the computational overhead required to achieve convergent results for the simulation of Raman amplification. The absence of collisional damping in available PIC codes is found to limit the parameter spaces within which simulations can be carried out. The conventional three-wave model has been extended to improve its accuracy, and to include the effects of plasma wave harmonics. In warm plasma, a new model is developed to estimate the fraction of trapped electrons, and their influence on the effective modulation depth of the plasma wave. Benchmarking against PIC codes shows strong agreement in regimes where the linearisation of the plasma response and Landau damping rates is valid. aPIC, an envelope-PIC implementation suitable for the investigation of Raman amplification, has been further developed to give improved numerical accuracy, allow the use of chirped pulses, and approximate the dispersive action of the plasma on the laser pulses. Benchmarking against full PIC codes shows good agreement. The code is used to identify a new regime of broad-bandwidth Raman amplification, with nonlinearity arising through high-amplitude plasma waves. Possible future improvements to the model and numerical implementation are outlined. The applicability of these models to the simulation of current experimental work at the University of Strathclyde is also considered.
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Rosa, Paweł. "Quasi-lossless data transmission with ultra-long Raman fibre laser based amplification." Thesis, Aston University, 2014. http://publications.aston.ac.uk/22442/.
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The project consists of an experimental and numerical modelling study of the applications of ultra-long Raman fibre laser (URFL) based amplification techniques for high-speed multi-wavelength optical communications systems. The research is focused in telecommunications C-band 40 Gb/s transmission data rates with direct and coherent detection. The optical transmission performance of URFL based systems in terms of optical noise, gain bandwidth and gain flatness for different system configurations is evaluated. Systems with different overall span lengths, transmission fibre types and data modulation formats are investigated. Performance is compared with conventional Erbium doped fibre amplifier based system to evaluate system configurations where URFL based amplification provide performance or commercial advantages.
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David, Pierre-Gérard. "Amplification laser et diagnostic temporel de paquets d'électrons ultra-relativistes en interaction laser-plasma." Paris 11, 2004. http://www.theses.fr/2004PA112286.
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La thèse dont ce manuscrit fait l’objet traite de deux des possibles applications de l’interaction d’un laser intense avec la matière. La première de ces applications est l’utilisation d’un plasma pour catapulter des particules à des énergies relativistes. Un plasma peut en effet supporter des champs électriques cent, voir mille fois supérieurs à ceux dans les matériaux classiques. Les lasers de puissance permettent d’exploiter cette capacité en engendrant d’importants champs électriques de sillage afin d’accélérer des électrons. Dans le présent manuscrit est étudié en particulier la mise ne place d’un nouveau diagnostic de mesure de durée pour les faisceaux d’électrons obtenus. Le diagnostic est basé sur une technique électro-optique et possède une excellente résolution. Son étude, sa mise en place, ses tests et ses premiers résultats sont présentés. La seconde application que couvre ce manuscrit est l’utilisation d’un plasma comme amplificateur laser, en régime dit de super-radiance. En effet, un amplificateur laser est un élément capable de transférer de l’énergie d’une source extérieure vers l’impulsion laser qui le traverse. Or un plasma, par le biais des ondes qu’il véhicule, est capable de réaliser ce transfert, tout en supportant des intensités bien supérieures aux techniques d’amplification traditionnelles. Si ce domaine d’étude est encore récent, sa maîtrise constitue pourtant un des développements clé qui pourrait conduire la technologie laser vers des seuils d’intensité encore jamais atteintThe present thesis relates of two specific applications of the laser-matter interaction scheme. The first of those applications is using a plasma as a relativistic particles accelerator. A plasma can actually support electric fields far beyond what classical materials are capable of. High intensity lasers can be used to generate large electric wake fields in order to accelerate electrons. The thesis discuss of such experiments and in particular of the integration of a new diagnostic to mesure the duration of the produced electron beams. The diagnostic is based on an electro-optic technic and has a very good resolution. Study, setup and first results are presented. The second application covered is the use of a plasma as a laser amplificator, in the so-called regime of super-radiance. Actually, a plasma is capable of transfering large amounts of energy from a laser beam to another via the waves it carries. Developping such a technic could be usefull to achieve laser intensities far beyond the actual limits. This field of study is only at its beginings, but some first results are presented
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Iqbal, Md Asif. "Advanced Raman amplification techniques for high capacity and broadband coherent optical transmission systems." Thesis, Aston University, 2018. http://publications.aston.ac.uk/37651/.
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This thesis presents a detailed study of different advanced Raman fibre laser (RFL) based amplification schemes and the development of novel broadband distributed and discrete Raman amplifiers in order to improve the transmission performance of modern high capacity, long-haul coherent optical systems. The numerical modelling of different Raman amplifier techniques including power distribution of signal, pump and noise components, RIN transfer from pump to signal, broadband gain optimization and so on have been described in details. The RIN and noise performances of RFL based distributed Raman amplifiers (DRAs) with different span lengths, forward pump powers and input reflection levels have been characterized experimentally. It has been shown through coherent transmission experiment that, in order to improve pump power efficiency, a low level of input reflection up to ~10% can be allowed without increasing the Q factor penalty > 1dB due to additional signal RIN penalty. A novel broadband (>10nm) first order Raman pump is developed for use as a forward pump in long-haul transmission experiment. Significant signal RIN mitigation up to 10dB compared with conventional low RIN, narrowband sources was obtained for bidirectional DRA schemes. Long-haul coherent transmission experiments with 10×120Gb/s DP-QPSK system were carried out in are circulating loop setup using the proposed broadband pump in bidirectional and backward only pumping configurations. The maximum transmission reach up to ~8330km was reported with first order broadband pumped bidirectional DRA, with transmission reach extensions of 1250km and1667km compared with conventional backward only and first order semiconductor pumped bidirectional pumping scheme respectively. Finally, a novel design of bidirectional broadband distributed DRA is proposed to reduce the noise figure tilt and improve the WDM transmission performances. Furthermore, broadband discrete Raman amplifier schemes in dual stage configuration are also shown for high gain, high output power, low noise and low nonlinear performances.
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Nasser, Nour. "Lumière lente par amplification paramétrique dans les fibres optiques biréfringentes." Thesis, Besançon, 2013. http://www.theses.fr/2013BESA2039/document.
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Cette thèse a pour thème le processus physique de ralentissement de la lumière induit par amplification paramétrique vectorielle dans les fibres optiques biréfringentes. Notre première étude porte sur la lumière lente induite par amplification paramétrique vectorielle dans les fibres fortement biréfringentes. Contrairement au processus scalaire, nous montrons théoriquement que le processus vectoriel offre la possibilité de créer des bandes de gain paramétrique étroites et éloignées de la pompe, permettant de générer des retards optiques très importants, un ordre de grandeur supérieurs à ceux obtenus en amplification paramétrique scalaire. Des résultats analytiques et issus de simulations numériques dans le cas de dispersion normale ainsi que dans le cas de dispersion anormale sont présentés. Ensuite, nous discutons des principales limitations au retard optique (élargissement de l’impulsion pompe notamment) et nous étudions l’influence positive de l’effet Raman sur le retard optique. Notre seconde étude est consacrée à la lumière lente induite par amplification paramétrique dans les fibres faiblement biréfringentes. Nous traitons l’ensemble des configurations possibles d’instabilité de polarisation selon l’état initial de polarisation de l’impulsion pompe et du régime de dispersion. Nous démontrons clairement que la configuration correspondant à une impulsion pompe polarisée suivant l’axe lent de la fibre et une impulsion signal polarisée suivant l’axe rapide en régime de dispersion normale donne des retards optiques les plus importantThis thesis aims to the physical process of slow light induced by vector parametric amplification in highly and weakly birefringent optical fibers. Our first study concerns slow light induced by parametric amplification in highly birefringent fibers. Unlike the scalar process, we theoretically demonstrate that large optical delays can be in principle generated in birefringent fibers, one order of magnitude higher than for the scalar case. Both analytical and numerical results in the case of anomalous dispersion are presented. We further discuss the main limitations for slow light optical delays (signal pulse broadening, pump pulse depletion). The influence of the Raman gain is also studied both analytically and numerically. The second study focuses on slow light induced by parametric amplification in weakly birefringent fibers. We consider all possible configurations of polarization modulation instability, depending on the polarization axis of the pump pulse and on the dispersion regime, and we derive the slow-light optical delays. We clearly demonstrate that the configuration corresponding to a pump pulse polarized in the slow axis of the fiber and a signal pulse polarized on the fast axis, in the normal dispersion regime, gives the largest optical delays
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Goel, Nitin Kumar. "Development of "Core-Suction" Technique for Fabrication of Highly Doped Fibers for Optical Amplification and Characterization of Optical Fibers for Raman Amplification." Diss., Virginia Tech, 2005. http://hdl.handle.net/10919/29302.
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This thesis presents a novel technique named "Core Suction" for fabricating optical fiber preforms for manufacturing highly doped fibers (HDFs) for optical amplification (Raman effect based or Erbium fiber based). The technique involves drawing the molten non-conventional core glass material into the silica cladding tube to form the preform. The developed technique is simple, inexpensive and shows great potential for fabricating preforms of highly nonlinear non-conventional multi-component glasses as the core material. Preforms were made with various core glasses such as Schott SF6, Lead-Tellurium-Germanate, Lead-Tellurium-Germanate- Neodymium -Erbium and MM2 in silica cladding tubes and then pulled into fibers.
The fabricated fibers were measured for refractive index profile, loss spectrum and spontaneous Raman spectra. Elemental analysis of the fiber samples was also performed using an electron microprobe. Erbium doped fiber amplifiers (EDFAs) were setup using 30 cm, 5cm and 1 cm lengths of fabricated erbium doped fibers and their gain spectra measured. The distributed gain spectrum for an EDFA was also measured using an optical frequency domain reflectometery (OFDR) technique. Commercial dispersion compensated fiber (DCF) with very high GeO2 doping was used to setup a Raman amplifier and the gain spectrum measured.
One of the needs of Raman amplification in optical fibers is to predict an accurate Raman gain, based on the fiber's refractive index profile. A method of predicting Raman gain in GeO2 doped fibers is presented and the predicted Raman gain values are compared with the measured ones in the same fibers. Raman gain issues like the dependence of the Raman gain on the GeO2 concentration, polarization dependence were taken into account for the gain calculations. An experimental setup for Raman gain measurements was made and measurement issues addressed. Polarization dependence of the Raman gain in one kilometer of polarization maintaining fiber was also measured.Ph. D.
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Hardy, Maxime. "Amplification d'impulsions brèves de haute énergie par effet Raman stimulé dans les fibres optiques." Master's thesis, Université Laval, 2016. http://hdl.handle.net/20.500.11794/27227.
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Le développement au cours des dernières décennies de lasers à fibre à verrouillage de modes permet aujourd’hui d’avoir accès à des sources fiables d’impulsions femtosecondes qui sont utilisées autant dans les laboratoires de recherche que pour des applications commerciales. Grâce à leur large bande passante ainsi qu’à leur excellente dissipation de chaleur, les fibres dopées avec des ions de terres rares ont permis l’amplification et la génération d’impulsions brèves de haute énergie avec une forte cadence. Cependant, les effets non linéaires causés par la faible taille du faisceau dans la fibre ainsi que la saturation de l’inversion de population du milieu compliquent l’utilisation d’amplificateurs fibrés pour l’obtention d’impulsions brèves dont l’énergie dépasse le millijoule. Diverses stratégies comme l’étirement des impulsions à des durées de l’ordre de la nanoseconde, l’utilisation de fibres à cristaux photoniques ayant un coeur plus large et l’amplification en parallèle ont permis de contourner ces limitations pour obtenir des impulsions de quelques millijoules ayant une durée inférieure à la picoseconde. Ce mémoire de maîtrise présente une nouvelle approche pour l’amplification d’impulsions brèves utilisant la diffusion Raman des verres de silice comme milieu de gain. Il est connu que cet effet non linéaire permet l’amplification avec une large bande passante et ce dernier est d’ailleurs couramment utilisé aujourd’hui dans les réseaux de télécommunications par fibre optique. Puisque l’adaptation des schémas d’amplification Raman existants aux impulsions brèves de haute énergie n’est pas directe, on propose plutôt un schéma consistant à transférer l’énergie d’une impulsion pompe quasi monochromatique à une impulsion signal brève étirée avec une dérive en fréquence. Afin d’évaluer le potentiel du gain Raman pour l’amplification d’impulsions brèves, ce mémoire présente un modèle analytique permettant de prédire les caractéristiques de l’impulsion amplifiée selon celles de la pompe et le milieu dans lequel elles se propagent. On trouve alors que la bande passante élevée du gain Raman des verres de silice ainsi que sa saturation inhomogène permettent l’amplification d’impulsions signal à une énergie comparable à celle de la pompe tout en conservant une largeur spectrale élevée supportant la compression à des durées très brèves. Quelques variantes du schéma d’amplification sont proposées, et leur potentiel est évalué par l’utilisation du modèle analytique ou de simulations numériques. On prédit analytiquement et numériquement l’amplification Raman d’impulsions à des énergies de quelques millijoules, dont la durée est inférieure à 150 fs et dont la puissance crête avoisine 20 GW.The development in the last decades of mode-locked fiber lasers resulted in the availability of reliable sources of femtosecond pulses that are both used for fundamental research and commercial applications. The wide gain bandwidth and excellent heat dissipation of rareearth-doped optical fibers have made possible the amplification and generation of high-energy ultrashort pulses with high repetition rates. However, phenomena such as nonlinear effects due to the small size of the beam and saturation of the population inversion in the gain medium tend to complicate their use for the amplification of pulses to energies exceeding the millijoule. Several strategies such as stretching the pulses to durations over the nanosecond, using photonic crystal fibers that have a wider core and parallelization have been used to circumvent these limitations, leading to pulses of a few millijoules with durations lower than a picosecond. This master’s thesis presents a novel approach for amplification of ultrashort pulses using stimulated Raman scattering in silica fibers as a gain mechanism. It is well known that this nonlinear effect allows the amplification with a wide bandwidth, such that it is nowadays commonly used in optical-fiber telecommunication networks. Because the adaptation of existing Raman amplification schemes to high-energy ultrashort pulses is not straightforward, we propose instead to transfer energy from a quasi-monochromatic pump pulse to a copropagating ultrashort signal pulse, stretched to comparable durations with a frequency chirp. In order to evaluate the potential of the Raman gain for the amplification of ultrashort pulses, this thesis presents an analytical model allowing the prediction of the amplified pulse’s features, depending upon those of the pump and upon the medium in which they are propagated. We thus find that the wide bandwidth of the Raman gain in silica glass, in addition to its inhomogeneous saturation, allows the amplification of signal pulses to energies of the same magnitude than that of the pump, while keeping their spectrum wide enough to support their compression to ultrashort durations. A few variants of the amplification scheme are presented, and their potential is evaluated using the analytical model or numerical simulations. We predict analytically and numerically the Raman amplification of pulses to energies of a few millijoules, whose durations are lower than 150 fs and having peak powers close to 20 GW.
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Nardou, Éric. "Nanoparticules métalliques en matrices vitreuses pour l’amplification Raman." Thesis, Lyon 1, 2011. http://www.theses.fr/2011LYO10207/document.
Full textAbstract:
Les fibres optiques utilisées pour le transfert d’information présentent des pertes de signal pendant leur propagation. Ainsi, ces signaux ont besoin d’être régulièrement amplifiés. De nos jours, l’Amplification Raman, basée sur le principe de diffusion Raman stimulée, est une des techniques utilisées pour réaliser ces amplifications. Les nanoparticules de métaux nobles ont des propriétés optiques uniques provenant de l’oscillation collective des électrons lorsqu’elles interagissent avec une onde électromagnétique. Ces particules absorbent fortement le champ électromagnétique à une fréquence appelée fréquence de résonance de plasmon de surface. Ce travail de thèse concerne l’influence des nanoparticules métalliques sur l’amélioration de l’Amplification Raman. Il s’inscrit dans le cadre du projet ANR Fenoptic (2010-2012), réunissant l’entreprise Draka et plusieurs laboratoires français (ICB Dijon, CMCP Paris, LPCML Lyon), qui s’intéressent à l’intégration des nanoparticules de métaux nobles à l’intérieur des fibres optiques afin d’utiliser la résonance de plasmon de surface pour améliorer l’efficacité des amplificateurs optiques. Dans ce travail, différentes sources de nanoparticules métalliques ont été examinées (suspensions, couches, préformes de fibre optique). Les expériences ont porté sur la caractérisation (forme et position du plasmon) de nanoparticules de métaux nobles incluses en matrices vitreuses ainsi que sur des mesures de spectroscopie Raman au travers desquelles le phénomène de Diffusion Raman Exaltée de Surface (SERS) a particulièrement été étudié. Pour la première fois, nous avons mis en évidence l’exaltation du signal Raman d’une matrice vitreuseSignals in optical fibers used for the transfer of information are attenuated due to impurities, scattering, absorption… To compensate for these losses, several techniques were developed like Erbium Doped Fiber Amplifier (EDFA). An alternative to rare earth doped fiber amplifier is Raman Amplification, which results from stimulated Raman scattering. Noble metal nanoparticles have optical properties induced by the collective oscillation of their conduction electrons when they interact with an electromagnetic wave. These particles strongly absorb the electromagnetic field at a frequency called surface Plasmon resonance frequency. This work is mainly based on effects leading to the improvement of the Raman Amplification. The ANR project Fenoptic (2010-2012), gathering Draka and several French laboratories (ICB (Dijon), CMCP (Paris), LPCML (Lyon)) is interested in the integration of noble metal nanoparticles in optical fibers using properties of the surface Plasmon resonance to improve the efficiency of optical amplifiers. In this work, different kinds of samples (suspensions, layers, optical fiber performs) with metal nanoparticles were studied. The experiments were based on the characterization (form and position of the Plasmon band) of noble metal nanoparticles in amorphous matrix and Raman spectroscopy was used to study the Surface Enhanced Raman Spectroscopy (SERS) effect. For the first time, we found the Raman signal exaltation of an amorphous matrix
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Provino, Laurent. "Génération et amplification contrôlées de très larges bandes spectrales dans les fibres optiques conventionnelles et microstructurées." Besançon, 2002. http://www.theses.fr/2002BESA2042.
Full textAbstract:
Ce manuscrit de thèse est organisé en deux parties. Une première partie théorique porte sur l'étude du processus d'amplification paramétrique de signaux faibles dans les fibres optiques, conventionnelles ou no linéaires, afin de concevoir des amplificateurs optiques à ultra-larges bandes spectrales et à profil de gain plat, deux critères essentiels permettant d'accroître les débits des transmissions multiplexées en longueur d'onde. Un second volet s'intéresse à une nouvelle génération de fibre en silice, la fibre microstructurée. Les propriétés peu communes de ces fibres ont été étudiées en développant un outil de modélisation original, basé sur la méthode de Galerkin vectorielle. La génération de supercontinuums spectraux dans ces fibres a été également démontrée à la fois en régimes nanoseconde et femtoseconde et analysée à partir de concepts théoriques analytiques et numériques. Enfin, les propriétés de maintien de polarisation de la fibre microstructurée ont été étudiéesThis PhD thesis manuscript is organized in two parts. The first, theoretical, part deals with fibre optical parametric amplification in conventional and highly non linear fibres. New amplifier schemes aimed at increasing the transmission rates of wavelength-division-multiplexed systems are proposed and characterized. Flat gain spectra over very large bandwidths are obtained using two pumps in a single fibre, or a single pump in a multi-section, dispersion-tailored fibre arrangement. The second part studies air-silica microstructured fibres. An efficient modelling tool based on the vectorial Galerkin method is developed in order to study their novel guiding and dispersion properties. Supercontinuum generation in these fibres is also demonstrated, both in the nanosecond and femtosecond pulse pumping regimes, and explained through analytical and numerical calculations. Finally, polarisation mode dispersion and vectorial modulational instability in the microstructured fibre are studied
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Guermache, Ali. "Etude et réalisation de lasers de pompe à 1480 nm pour l'amplification Raman." Phd thesis, Télécom ParisTech, 2005. http://pastel.archives-ouvertes.fr/pastel-00001247.
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L'étude concerne les lasers de puissance à semi-conducteurs émettant aux alentours de 1480nm dont l'utilisation principale est l'amplification Raman dans les fibres optiques pour les futurs systèmes de télécommunications. Cette amplification nécessite des puissances de pompe supérieures à 400mW. Les travaux ont porté sur la conception et la caractérisation des lasers de pompe en vue d'une augmentation de la puissance de sortie. Après avoir identifier les principaux effets limitant la puissance des pompes (effets thermiques, Longitudinal Spatial Hole Burning, pertes internes), trois solutions ont été mises en œuvre au cours de cette thèse pour réduire ces effets. Nous avons montré que l'introduction de guide large multimode (MMI) permettait à la fois une réduction des effets thermiques et une augmentation de la puissance de saturation de l'ordre de 10% en comparaison au laser à ruban droit. La cavité évasée a permis une réduction du Longitudinal Spatial Hole Burning entraînant un gain en puissance de saturation de l'ordre de 30% avec une puissance de 625mW pour un courant de 2.5A. Enfin, la diminution des pertes internes via l'utilisation d'un quaternaire faible indice coté InP dopé n (structure à "cladding asymétrique") a permis l'obtention d'un record de puissance (1 Watt couplé sous 5A) dans une fibre monomode avec un guide à ruban droit.
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Benoit, Aurélien. "Sources laser fibrées hybrides de haute puissance : Amplification et conversion de fréquences." Thesis, Limoges, 2015. http://www.theses.fr/2015LIMO0024/document.
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Les lasers à fibre de haute puissance constituent depuis une dizaine d’année un outil pertinent pour un nombre croissant d’applications. Dans le cadre d’un contrat CIFRE entre la société Eolite Systems et le laboratoire Xlim (UMR 7252 du CNRS et de l’Université de Limoges), mon projet de thèse a consisté à développer les briques technologiques de futures sources lasersHigh-power fiber lasers adress an increasing number of applications since ten years. In the frame of a CIFRE contract between the company Eolite Systems and Xlim (joint laboratory between CNRS and the University of Limoges), the goal of this PhD project was to develop the technological blocs to achieve all-fibre high-power lasers emiting out of the conventional spectral band covered by existing lasers.Modal instabilities in large mode area (LMA) fibers are currently the main limitation of the fiber lasers power scaling. We have experimentally demonstrated the relevance of inner cladding aperiodic structures to efficiently delocalize higher order modes outside the gain region. A systematic study of passive fibers based on such structures has shown the single propagation of the fundamental mode over a wide wavelength range from 1 to 2 µm for dimension of core up to 85 µm. This effective mode delocalization even extends up to a core dimension of 140 µm at a 2 µm wavelength.The combination of high power picosecond fiber laser with an average power of 22.7 W and a hydrogen-filled inhibited coupling Kagome fiber allowed us to generate two Raman combs over five frequency octaves from 321 nm to 12.5 µm. These two combs are controlled by the laser pump polarization and generated an average power of 10.1 W displayed over 70 laser lines for circular pump polarization and 8.6 W over 30 lines for linear polarization. Some laser lines within these combs have been generated for the first time from high-power fiber source in the mid-infrared range. We have also demonstrated the generation of high-power line by optimizing the first vibrational Stokes at 1.8 µm with an average power of 9.3 W and a quantum efficiency of the frequency conversion stage close to 80%
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Paiva, Getúlio Eduardo Rodrigues de. "Estudo de esquemas de amplificação para redes PON de longo alcance." Universidade de São Paulo, 2012. http://www.teses.usp.br/teses/disponiveis/18/18155/tde-07052012-095117/.
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O surgimento de novos serviços que requerem uma largura de banda cada vez maior, bem como o crescente número de usuários de tais serviços, têm introduzido desafios às empresas operadoras de telecomunicações em sua capacidade de atender a estas demandas sem perda apreciável da qualidade de serviço e mantendo, ainda assim, os custos num nível aceitável pelos usuários. Neste contexto, redes ópticas passivas (PONs) vêm atraindo grande interesse em anos recentes. Na sua variante de longo-alcance, as redes PON permitem uma consolidação do uso dos equipamentos e centrais de serviço requeridos, reduzindo custos operacionais e de instalação. Uma das formas de atingir este maior alcance dá-se por meio da inserção de amplificadores ópticos nas redes de acesso. Neste trabalho, portanto, estudaram-se alguns tipos de amplificadores ópticos e suas possíveis aplicações em redes de acesso, levando a topologias de longo alcance e alta capacidade. Foram realizadas avaliações experimentais de um extensor, baseado em amplificadores ópticos semicondutores (SOAs), na rede GPON do CPqD, sob a Meta 3 do Projeto GIGA, possibilitando a obtenção de uma topologia do tipo Fiber-to-the-Building (FTTB) com 80 km de extensão e 128 usuários atendidos por uma única central de serviço. Além dessas validações experimentais, foram simulados computacionalmente SOAs com características otimizadas bem como sistemas que utilizam fibras dopadas com érbio bombeadas remotamente, sendo que nestes últimos, atingiram-se distâncias superiores a 100 km.The emergence of new services which require an increasing bandwidth, as well as the growing number of users of such services, have introduced challenges to the network operators in regard to their capacity of supporting these demands with no penalty on the required quality of service, while keeping the costs at an acceptable level for the users. In this context, passive optical networks (PONs) have attracted a great deal of interest in recent years. In the long-reach configuration, PON networks allow for a consolidation of equipament usage, reducing operational and installation costs. One way to achieve this longer reach is by the insertion of optical amplifiers in the access network. Therefore, in our work, we have investigated several optical amplifier configurations, as well as their application in access networks, leading to longreach and high capacity network topologies. Experimental evaluations of an extender, based on semiconductor optical amplifiers, were carried out in the CPqD GPON network, under Goal 3 of GIGA Project, allowing the achievement of a Fiber-to-the-Building (FTTB) topology with 80km of extension and 128 users served by a single central office. Besides these experimental validations, were simulated computationally SOAs with optimized characteristics as well as systems using remotely pumped erbium-doped fibers, whereas in the latter were reached distances exceeding 100 km.
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Sylvestre, 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.
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Cette thèse porte sur une étude détaillée, théorique et expérimentale, des phénomènes paramétriques, de la diffusion Raman stimulée et de leurs interactions mutuelles, survenant lors de la propagation d'ondes électromagnétiques intenses dans les fibres optiques unimodales. Ce travail vise notamment à suggérer de nouvelles fonctions de traitement tout-optique pour les télécommunications par fibres optiques. Une partie importante du travail met à profit la forte biréfringence des fibres à maintien de polarisation pour réaliser l'amplification paramétrique (ou instabilité de modulation induite) de signaux impulsionnels dans le régime de dispersion normale. Une approche phénoménologique montre l'équivalence physique entre le mélange à quatre ondes et l'instabilité de modulation. L'amplification de la fluorescence paramétrique, à partir du bruit quantique, présente un gain quasi-exponentiel en fonction de la puissance de pompe alors que l'amplification d'un signal évolue selon une loi en cloche à cause du déphasage non linéaire induit par la pompe. Les résultats expérimentaux mettent en évidence cette dynamique en cloche et confirment la validité du modèle d'instabilité de modulation. En remplacement des sources impulsionnelles de puissance, une expérience supplémentaire utilisant des microlasers permet d'obtenir des gains supérieurs à 20 dB dans 20 m de fibre. Enfin l'étude des aspects temporels liés à l'amplification paramétrique par biréfringence révèle la génération de trains d'impulsions solitons noirs à des cadences supérieures au THz. Une partie complémentaire analyse le processus d'intermodulation de phase dégénérée dans une fibre biréfringente et permet de décrire les effets spectraux et temporels, liés à l'utilisation d'impulsions picosecondes, qui affectent la propagation des ondes sur les axes de polarisation de la fibre. Les effets combinés de l'intermodulation de phase et de la différence de temps de groupe provoquent des rétrécissements et des asymétries des spectres modulés ainsi que des modulations temporelles rapides, en comparaison avec la situation ou une impulsion est polarisée selon une ligne neutre. Cette comparaison permet de mesurer la biréfringence des fibres sur une grande dynamique (103) et une bonne précision (5%). Une expérience montre ensuite la possibilité de décaler en fréquence des signaux par in termodulation de phase dégénérée sur une plage de 0 à ± 0,3 nm. Le troisième volet étudie les effets de couplage entre le mélange à quatre ondes et la diffusion Raman stimulée (DRS) en régime de dispersion normale pour réaliser de la conversion en longueur d'onde. Un signal picoseconde à la fréquence Raman anti-Stokes, injecté avec une impulsion pompe, induit la génération d'une impulsion Stokes par couplage paramétrique. La longueur de couplage, très faible, est cependant suffisante pour que l'amplification Raman Stokes prenne ensuite le relais, même très en dessous du seuil de DRS habituel. Cette méthode est originale puisqu'elle démarre sur un processus paramétrique complètement désaccordé en phase, mais assisté par l'amplification Raman Stokes et l'absorption anti-Stokes. Il permet ainsi une conversion/amplification tout-optique ultra-rapide de fréquences avec de très grands décalages spectraux (26 THz), normalement inaccessibles à la conversion paramétrique pure. Une application intéressante de ce procédé réside dans la possibilité de réaliser une conversion de longueur d'onde 1,3 Μm↑1,5 Μm entre les deux fenêtres spectrales des télécommunications. Bien que la diffusion Raman stimulée (DRS) dans les fibres optiques puisse être mise à profit pour un certain nombre d'applications, ce même processus peut être également source de pénalité en puissance et en débit dans les systèmes de télécommunications, notamment les transmissions multiplexées en longueur d'onde (WDM). Une méthode de contrôle et de suppression de la DRS est démontré à partir d'un champ de pompe multi-fréquences. Le mécanisme de suppression, basé sur l'antisymétrie spectrale de la susceptibilité Raman, est optimisé pour un écart entre les différentes composantes spectrales de pompe égal à deux fois le décalage Raman.. La suppression totale de la DRS est obtenue en déséquilibrant les puissances de pompe de manière à contrebalancer l'effet additionnel de cascade Raman des hautes vers les basses fréquences. Outre les implications potentielles de cette méthode dans les transmissions WDM, ce principe de suppression présente un intérêt pour augmenter les facteurs de compression dans les compresseurs d'impulsions à fibre.
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Nardou, Éric. "Nanoparticules métalliques en matrices vitreuses pour l'amplification Raman." Phd thesis, Université Claude Bernard - Lyon I, 2011. http://tel.archives-ouvertes.fr/tel-00740971.
Full textAbstract:
Les fibres optiques utilisées pour le transfert d'information présentent des pertes de signal pendant leur propagation. Ainsi, ces signaux ont besoin d'être régulièrement amplifiés. De nos jours, l'Amplification Raman, basée sur le principe de diffusion Raman stimulée, est une des techniques utilisées pour réaliser ces amplifications. Les nanoparticules de métaux nobles ont des propriétés optiques uniques provenant de l'oscillation collective des électrons lorsqu'elles interagissent avec une onde électromagnétique. Ces particules absorbent fortement le champ électromagnétique à une fréquence appelée fréquence de résonance de plasmon de surface. Ce travail de thèse concerne l'influence des nanoparticules métalliques sur l'amélioration de l'Amplification Raman. Il s'inscrit dans le cadre du projet ANR Fenoptic (2010-2012), réunissant l'entreprise Draka et plusieurs laboratoires français (ICB Dijon, CMCP Paris, LPCML Lyon), qui s'intéressent à l'intégration des nanoparticules de métaux nobles à l'intérieur des fibres optiques afin d'utiliser la résonance de plasmon de surface pour améliorer l'efficacité des amplificateurs optiques. Dans ce travail, différentes sources de nanoparticules métalliques ont été examinées (suspensions, couches, préformes de fibre optique). Les expériences ont porté sur la caractérisation (forme et position du plasmon) de nanoparticules de métaux nobles incluses en matrices vitreuses ainsi que sur des mesures de spectroscopie Raman au travers desquelles le phénomène de Diffusion Raman Exaltée de Surface (SERS) a particulièrement été étudié. Pour la première fois, nous avons mis en évidence l'exaltation du signal Raman d'une matrice vitreuse.
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Chiarello, Fabrizio. "Analysis and application of nonlinear amplification effects in single-mode optical fibers." Doctoral thesis, Università degli studi di Padova, 2014. http://hdl.handle.net/11577/3423797.
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This thesis focuses on all-optical signal generation and processing through nonlinear amplification phenomena in single-mode fibers.
Three different nonlinear fiber optical oscillators are investigated and experimentally demonstrated. A continuous-wave pump for fiber Raman amplifiers, developed with the goal of achieving high degree of polarization, tunability and suppression of stimulated Brillouin scattering, is presented, discussed and used to achieve nonlinear polarization attraction. A fast and widely tunable fiber optical oscillator based on stimulated Raman scattering and on broad- and narrow-band fiber optical parametric amplification, and exploiting the time-dispersion-tuning technique, is demonstrated and characterized. Each nonlinear effect dominates in a different spectral region, so that the fiber optical oscillator achieves a tuning range of 160 nm. Through the same time-dispersion-tuning method, a fast tunable optical frequency comb, based on cascaded four-wave mixing, is obtained by using a single pump, avoiding the limitations in spectral purity and frequency and phase stability given by double pump systems.
Finally, the control of the state of polarization and of the degree of polarization through nonlinear polarization attraction in counter-propagating fiber Raman amplifiers in standard, randomly birefringent, single-mode fibers is studied, analyzed and characterized. The analysis, including the effects of pump depletion, nonlinear polarization rotation and orthogonal Raman gain, shows that counter-propagating fiber Raman amplifiers are effective in attracting the signal toward a predetermined state of polarization settled by the pump input state of polarization. Moreover, the importance of the role of pump depletion in achieving signal repolarization in fibers with moderately-high polarization-mode dispersion is discussed. The performances and the limits of repolarization efficiency are determined, leading to a quantitative relationship between the degree of polarization and the gain of the fiber Raman amplifier, which is then confirmed to represent an upper bound on the maximum achievable degree of polarization.Questa tesi è focalizzata sulla generazione e sull’elaborazione completamente ottiche di segnali attraverso fenomeni di amplificazione non lineare in fibre ottiche a singolo modo. Tre diversi oscillatori non lineari in fibra ottica sono investigati e dimostrati sperimentalmente. Una pompa ad onda continua per amplificatori Raman in fibra, sviluppata con l’obiettivo di ottenere un alto grado di polarizzazione, sintonizzabilità e soppressione dell’effetto Brillouin, è presentata, discussa e utilizzata al fine di ottenere attrazione di polarizzazione non lineare. Un oscillatore in fibra ottica con sintonia veloce su un’ampia banda basato sugli effetti di amplificazione Raman e di amplificazione parametrica a banda stretta e a banda larga, che sfrutta la tecnica di sintonia mediante dispersione temporale (time-dispersion tuning), è dimostrato e caratterizzato. Ciascuno degli effetti non lineari domina in una diversa regione spettrale, cosicché l’oscillatore raggiunge un intervallo di sintonia di 160 nm. Attraverso lo stesso metodo di sintonia mediante dispersione temporale, un comb ottico in fibra con sintonia veloce, basato sull’effetto di miscelazione a quattro onde a cascata, è ottenuto usando una singola pompa, evitando così i limiti di purezza spettrale e di stabilità di frequenza e di fase dei sistemi a doppia pompa. Infine, il controllo dello stato e del grado di polarizzazione, attraverso l’attrazione di polarizzazione non lineare in amplificatori Raman in fibra ottica standard con birifrangenza aleatoria, è studiato, analizzato e caratterizzato. L’analisi, che include gli effetti di svuotamento della pompa, della rotazione non lineare di polarizzazione e di guadagno Raman ortogonale, mostra che gli amplificatori Raman contro-propaganti sono efficaci nell’attrarre il segnale verso uno stato di polarizzazione predeterminato e imposto dallo stato di polarizzazione di ingresso della pompa. Viene inoltre discussa l’importanza del ruolo dello svuotamento della pompa nell’ottenere la ripolarizzazione del segnale in fibre con dispersione dei modi di polarizzazione moderatamente alta. Le prestazioni e i limiti dell’efficienza di ripolarizzazione vengono determinati portando ad una relazione quantitativa tra il grado di polarizzazione e il guadagno dell’amplificatore Raman, relazione che rappresenta un limite superiore sul massimo grado di polarizzazione raggiungibile.
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Finot, Christophe. "Similaritons dans les amplificateurs Raman à fibre optique." Phd thesis, Université de Bourgogne, 2005. http://tel.archives-ouvertes.fr/tel-00011124.
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Ce mémoire présente la génération de similaritons dans un amplificateur Raman à dispersion normale aux longueurs d'onde des télécommunications optiques. Les profils temporels expérimentaux obtenus par caractérisation FROG mettent en évidence un profil d'intensité parabolique associé à une dérive de fréquence linéaire, en accord avec les résultats d'un modèle numérique.Différentes propriétés théoriques des similaritons sont ensuite vérifiées expérimentalement. La dynamique de deux impulsions similaritons à des longueurs d'ondes centrales identiques ou différentes est également étudiée : les similaritons sont robustes vis-à-vis des collisions alors que l'interaction de deux similaritons entraîne la génération d'un train de solitons noirs à haut-débit.
Dans une dernière partie, nous évoquons l'application des similaritons à trois domaines : la génération d'impulsions ultracourtes, la mise en forme d'impulsions et enfin la régénération optique de signaux télécom à haut-débit.
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Freedman, Benjamin Gordon. "Degenerate oligonucleotide primed amplification of genomic DNA for combinatorial screening libraries and strain enrichment." Diss., Virginia Tech, 2014. http://hdl.handle.net/10919/71346.
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Combinatorial approaches in metabolic engineering can make use of randomized mutations and/or overexpression of randomized DNA fragments. When DNA fragments are obtained from a common genome or metagenome and packaged into the same expression vector, this is referred to as a DNA library. Generating quality DNA libraries that incorporate broad genetic diversity is challenging, despite the availability of published protocols. In response, a novel, efficient, and reproducible technique for creating DNA libraries was created in this research based on whole genome amplification using degenerate oligonucleotide primed PCR (DOP-PCR). The approach can produce DNA libraries from nanograms of a template genome or the metagenome of multiple microbial populations. The DOP-PCR primers contain random bases, and thermodynamics of hairpin formation was used to design primers capable of binding randomly to template DNA for amplification with minimal bias. Next-generation high-throughput sequencing was used to determine the design is capable of amplifying up to 98% of template genomic DNA and consistently out-performed other DOP-PCR primers.
Application of these new DOP-PCR amplified DNA libraries was demonstrated in multiple strain enrichments to isolate genetic library fragments capable of (i) increasing tolerance of E. coli ER2256 to toxic levels of 1-butanol by doubling the growth rate of the culture, (ii) redirecting metabolism to ethanol and pyruvate production (over 250% increase in yield) in Clostridium cellulolyticum when consuming cellobiose, and (iii) enhancing L-arginine production when used in conjunction with a new synthetic gene circuit.Ph. D.
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Araujo, Alfredo Almeida de. "Análise de amplificação Raman em fibras microestruturadas de baixa perda." Universidade Presbiteriana Mackenzie, 2008. http://tede.mackenzie.br/jspui/handle/tede/1485.
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Previous issue date: 2008-02-13This dissertation aims to describe the basic characteristics of microstructured fibers, their concept and performance, and to investigate the application of a low loss microstructured fiber to the development of Raman amplifiers. An analysis of the use of these amplifiers in Telecommunication applications is described. To this end, simulations were carried out with these waveguides with the data of a real fiber described in the literature. Simulations were also carried out to determine the amplifier s net gain and noise figure and to establish the advantages of its use in a complete optical fiber span, including the compensation dispersion in the O band (1260-1360 nm). As a result, it was demonstrated that the microstructured fiber presents, in some aspects, a performance that is higher than that of conventional Raman amplifiers, and complementary to that of a commercial amplifiers, such as those based on Erbium doped fiber.
Esta dissertação tem como objetivo descrever as características básicas das fibras microestruturadas, seu conceito e desempenho, e investigar a aplicação de uma fibra microestruturada de baixa perda para o desenvolvimento de amplificadores Raman. Uma análise do uso destes em aplicações de Telecomunicações é descrita. Para isso, foram realizadas simulações destes guias de onda com dados de uma fibra real descrita na literatura. Também foram realizadas simulações para verificação do ganho líquido e figura de ruído de um amplificador baseado nesta fibra e das vantagens de seu uso em um enlace óptico completo, incluindo compensação de dispersão para sinais da banda O (1260-1360 nm). Como resultado, demonstrou-se um desempenho superior em alguns aspectos aos amplificadores Raman convencionais, e complementar aos amplificadores disponíveis atualmente no mercado, como os baseados em fibra dopada com Érbio.
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Andrasik, Stephen James. "NEW ORGANIC/INORGANIC HYBRID SOL-GEL NANOCOMPOSITE MATERIALS FOR RAMAN GAIN IN FIBER OPTICS." Master's thesis, University of Central Florida, 2004. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/4457.
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The recent increased availability of additional wavelengths in the telecommunications window of about 1300-1600 nm has generated an interest in new optical materials and devices that can operate outside the normally used regions of 840 nm, 1310 nm, and 1550 nm. Specifically, methods to amplify fiber optical data transmission in the regions where there is limited or no existing methods to achieve amplification is of interest in the chemistry and photonic communities. Raman gain is one method that has been proposed to passively amplify optical data transmission through a distributed process. Amplification is obtained through a nonlinear light scattering process where an optical wave is amplified at the expense of a higher frequency pump wave. Multiple wavelengths can be evenly amplified simultaneously in a desired region by specific selection of one or more pump wavelengths. Herein, the synthesis and characterization of new hybrid inorganic/organic sol-gels and monomers capable of producing broad wavelength Raman scattering over a spectral range of 1200-1670 nm are presented. The synthetic methodology developed facilitates the systematic approach to produce sol-gel derivatives with functional groups known to be strongly Raman scattering. Additionally, a method to synthesize and characterize a large number of different compounds using a combinatorial approach was demonstrated. Thio based derivatives of sulfonyldiphenol, isopropylidenediphenol, and triallyloxy triazine were synthesized in addition to thio derivatives of poly(hydroxystyrene). Micro-Raman spectra of the hybrid sol-gels, thio-based derivatives, and IR spectra of select sol-gel monomers were obtained.M.S.
Department of Chemistry
Arts and Sciences
Chemistry
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Toledo, Jair Fiuza de. "Análise de um amplificador Raman distribuído nas bandas S+ e S utilizando a fibra óptica TrueWave® Reach Low Water Peak." Universidade Presbiteriana Mackenzie, 2006. http://tede.mackenzie.br/jspui/handle/tede/1421.
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Previous issue date: 2006-08-29The performance of a distributed Raman amplifier at S - Band using the TrueWave® Reach Low Water Peak fiber in a 100km span is analyzed through numerical simulations. The manufacturer, the OFS Fitel Denmark Ap, has experimentally characterized the physical parameters of the fiber, such as, attenuation, dispersion and Raman gain efficiency at Band - S. The low fiber attenuation around pump wavelength region, around 0,34dB/km at 1370nm, allow the achievement of approximately 10dB over 70nm in the S - Band − using 4 (four) pump lasers with pump power on the order of tenth of mWatts .
O desempenho de um amplificador Raman distribuído na Banda - S utilizando a fibra óptica TrueWave® Reach Low Water Peak em um enlace de 100km é analisado através de simulações numéricas. O fabricante, a OFS Fitel Denmark Ap, caracterizou experimentalmente os parâmetros físicos da fibra óptica, tais como atenuação, dispersão, e eficiência de ganho Raman na Banda - S. A baixa absorção dessa fibra óptica na região espectral onde se localizam os lasers de bombeamento, em torno de 0,34dB/km, para 1370nm, permite a utilização de 4 lasers de bombeamento com potências da ordem de dezenas de mWatts, para garantir um ganho on-off da ordem de 10dB em 70nm (1460 a 1530nm) na Banda - S.
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Ramos, Igor da Silva. "Análise sistêmica da compensação de dispersão e amplificação Raman em fibras microestruturadas." Universidade Presbiteriana Mackenzie, 2009. http://tede.mackenzie.br/jspui/handle/tede/1501.
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Previous issue date: 2009-02-03Fundo Mackenzie de Pesquisa
This work studies, through systemic modeling a microstructured optical fiber used in a module for dispersion compensation and Raman amplification for optical communication systems. The use of this device compensates the dispersion in a range of frequencies not covered by conventional dispersion compensating fibers and, simultaneously, amplifies the signal in order to reach longer transmission distances. In particular, dispersion compensation and amplification is demonstrated in the O Band (1260 nm up to 1360 nm) for systems operating at 10 and 40 Gbps. For this purpose, the parameters of a real microstructured optical fiber model are used in the VPI TransmissionMaker numerical simulation software through which is possible to evaluate the performance of the device. The performance evaluation is carried out through Bit Error Rate (BER) as a function of link distance and transmission channel wavelength.
Este trabalho estuda através de modelamento sistêmico, uma fibra óptica microestruturada utilizada em um módulo de compensação de dispersão e amplificação Raman de sistemas ópticos. O uso deste dispositivo compensa a dispersão em faixas de freqüência não cobertas por fibras de compensação de dispersão convencionais e simultaneamente amplifica o sinal a fim de permitir maiores distâncias de transmissão. Em particular, compensação de dispersão e amplificação são demonstradas na banda O (1260 nm a 1360 nm) para sistemas operando a taxas de 10 e 40 Gbps. Para isso, são utilizadas as características de um modelo de fibra microestruturada real no software de simulação numérica VPI TransmissionMaker por meio do qual é possível avaliar o desempenho deste dispositivo. A avaliação de desempenho é feita através de curvas de taxa de erro de bits (BER, do inglês Bit Error Rate) em função do comprimento do enlace e comprimento de onda do canal de transmissão.
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Sunday, Christopher Edozie. "The design of ultrasensitive immunosensors based on a new multi-signal amplification gold nanoparticles-dotted 4-nitrophenylazo functionalised graphene sensing platform for the determination of deoxynivalenol." Thesis, University of Western Cape, 2014. http://hdl.handle.net/11394/3361.
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Philosophiae Doctor - PhDA highly dispersive gold nanoparticle-dotted 4-nitrophenylazo functionalised graphene nanocomposite (AuNp/G/PhNO2) was successfully synthesised and applied in enhancing sensing platform signals. Three label-free electrochemical immunosensors for the detection of deoxynivalenol mycotoxin (DON) based on the systematic modification of glassy carbon electrodes (GCE) with AuNp/G/PhNO2 was effectively achieved. General electrochemical impedance method was employed for the sensitive and selective detection of DON in standard solutions and reference material samples. A significant increase in charge transfer resistance (Rct) of the sensing interface was observed due to the formation of insulating immune-complexes by the binding of deoxynivalenol antibody (DONab) and deoxynivalenol antigen (DONag). Further attachments of DONab and DONag resulted in increases in the obtained Rct values, and the increases were linearly proportional to the concentration of DONag. The three immunosensors denoted as GCE/PDMA/AuNp/G/PhNH2/DONab, GCE/Nafion/[Ru(bpy)3]2+/AuNp/G/PhNH2/DONab and GCE/Nafion/[Ru(bpy)3]2+/G/PhNH2/DONab have detection range of 6 – 30 ng/mL for DONag in standard samples. Their sensitivity and detection limits were 43.45 ΩL/ng and 1.1 pg/L; 32.14ΩL/ng and 0.3 pg/L; 9.412 ΩL/ng and 1.1 pg/L respectively. This result was better than those reported in the literature and compares reasonably with Enzyme Linked Immunosorbent Assay (ELISA) results. The present sensing methodology represents an attractive alternative to the existing methods for the detection of deoxynivalenol mycotoxin and other big biomolecules of interest due to its simplicity, stability, sensitivity, reproducibility, selectivity, and inexpensive instrumentation. And they could be used to develop high-performance, ultra-sensitive electrochemiluminescence, voltammetric or amperometric sensors as well.
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Petit, Laëticia. "Amplification optique dans des verres borophosphate de niobium et tellurite dopés aux ions de terres rares présentant un indice optique non linéaire élevé." Phd thesis, Université Sciences et Technologies - Bordeaux I, 2002. http://tel.archives-ouvertes.fr/tel-00003919.
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Ce travail s'insère, non seulement, dans la compréhension de la relation entre la résonance des terres rares et l'indice non linéaire, mais aussi, dans la recherche de nouveaux matériaux dopés terres rares pour la commutation optique. L'introduction d'oxyde d'erbium dans des verres tellurites et borophosphates de niobium, présentant intrinsèquement une non linéarité optique de 3ème ordre élevée, a été étudiée. Il a été montré qu'il est possible de contrôler le gain et la non linéarité de matériaux dopés grâce à la corrélation établie entre l'analyse structurale et l'étude des propriétés spectroscopiques, de gain et de non linéarité qui dépendent des probabilités de transition 4f –4f. L'ensemble des résultats permet de mieux comprendre et prédire la variation de l'indice non linéaire d'un matériau amplificateur.
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Pickartz, Sabrina. "All-optical control of fiber solitons." Doctoral thesis, Humboldt-Universität zu Berlin, 2018. http://dx.doi.org/10.18452/19468.
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Das Thema dieser Arbeit ist eine mögliche Steuerung eines optischen Solitons in nichtlinearen optischen Fasern. Es gelang, die interessierenden Solitonparameter wie Intensität, Dauer und Zeitverschiebung durch die Wechselwirkung mit einer dispersiven Welle geringer Intensität kontrollierbar zu modifizieren.
Es wird eine neue analytische Theorie vorgestellt für die Wechselwirkung zwischen Solitonen und dispersiven Wellen, die auf der Kreuzphasenmodulation in nichtlinearen Fasern beruht. Das vorgestellte Modell kombiniert quantenmechnische Streutheorie und eine Erweiterung der Störungstheorie für Solitonen aus der nichtlinearen Optik. Damit wurden folgende neue Ergebnisse erzielt: (1) Die Entwicklung aller Solitonparameter wird korrekt vorhergesagt. Insbesondere wird die mögliche Verstärkung der Solitonamplitude erfolgreich bestimmt. (2) Passende Intervalle der Kontrollparameter, die eine effektive Solitonmanipulation garantieren, können quantitativ bestimmt werden. (3) Der Raman-Effekt wurde in die Modellbeschreibung eingebunden. Die klassische Abschätzung der Eigenfrequenzverschiebung des Solitons durch den Raman-Effekt wurde verbessert und erweitert durch eine neue Relation für den einhergehenden Amplitudenverlust. Weiterhin wurden solche Kontrollpulse bestimmt, die dieser Schwächung des Solitons entgegenwirken. Im Unterschied zu früheren Versuchen liefert die hier entwickelte Modellbeschreibung die passenden Parameterbereiche für eine stabile Auslöschung des Raman-Effektes. (4) Obwohl die Wechselwirkung selbst auf der Kreuzphasenmodulation basiert, spielt der ”self-steepening“- Effekt, der die Bildung von optischen Schocks beschreibt, eine entscheidende Rolle für eine effiziente Veränderung der Solitonparameter.This work discusses the problem how to control an optical soliton propagating along a non- linear fiber. The approach chosen here is to change soliton delay, duration and intensity in a simple, predictable manner by applying low-intensity velocity-matched dispersive light waves. A new analytic theory of cross-phase modulation interactions of solitons with dispersive control waves is presented which combines quantum mechanical scattering theory, a modified soliton perturbation theory and a multi-scale approach. This led to the following new results: (1) The evolution of all soliton parameters is correctly predicted. In particular the possible amplitude enhancement of solitons is successfully quantified, which could not be obtained by the standard formulation of the soliton perturbation theory. (2) General ranges for control parameters are quantitatively determined, which ensure an effective interaction. (3) The Raman effect is incorporated into the theory. The classical estimation of the Raman self-frequency shift is refined and expanded by a new relation for the amplitude loss arising with the Raman self-frequency shift. Furthermore, control pulses are identified which cancel soliton degradation due to Raman effect. In contrast to previously reported attempts with the interaction scheme under consideration, even parameter ranges are found which lead to a stable cancellation of the Raman effect. (4) New qualitative insights into the underlying process emerged. The prominent role of the self-steepening effect could be isolated. Though the pulse interaction is mediated by cross-phase modulation, the self-steepening effect causes an essential enhancement leading to much stronger changes in soliton parameters.
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Olmedo, Herrero Elena. "Étude des effets non linéaires dans les lasers et amplificateurs de puissance à fibre double gaine dopée Er3+/Yb3+." Phd thesis, Télécom ParisTech, 2003. http://pastel.archives-ouvertes.fr/pastel-00000743.
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Depuis quelques années, nous assistons à une augmentation soutenue de la demande en puissance des sources optiques. L'introduction des fibres à double gaine dopées Er3+/Yb3+ dans la conception des lasers et des amplificateurs a permis l'obtention de puissances très élevées, impossibles à imaginer quelques années auparavant. L'évolution de cette technologie, conçue en principe pour des systèmes télécom, permet d'envisager de nombreuses applications dans d'autres secteurs tels que le médical, la découpe laser, le marquage, le lidar, le perçage, le soudage, ou le traitement de surface, entre autres. Du fait des fortes puissances mises en jeu dans de tels composants, l'apparition des effets non linéaires devient incontournable. Les effets non linéaires sont à l'origine d'interférences ou de distorsions qui dégradent considérablement les signaux. La compréhension de ces effets devient donc indispensable dans l'optique de trouver des règles d'ingénierie aidant à les minimiser lors de la conception de nouveaux composants. Ce mémoire présente une contribution, à la fois théorique et expérimentale, à l'étude des effets non linéaires dans les lasers et amplificateurs de puissance à fibre double gaine dopée Er3+/Yb3+, portant plus particulièrement sur l'automodulation de phase et la diffusion Brillouin stimulée. L'automodulation de phase a été traitée dans le cas des impulsions d'une durée inférieure à 4 ps. Après une mise en évidence expérimentale, un outil de simulation a été créé à l'aide de l'équation de Schrödinger non linéaire avec gain. Afin d'obtenir des impulsions de puissance supérieure à celle imposée par l'automodulation de phase, un système d'amplification d'impulsions utilisant l'architecture CPA ('Chirped Pulse Amplification') a été mis en place, permettant l'obtention d'impulsions de 450 fs avec une puissance crête supérieure à 35 kW. Dans le cas des impulsions larges -d'une durée supérieure à 10 ns-, la puissance maximum de sortie est limitée par un autre effet: la diffusion Brillouin stimulée. Cet effet a également été mis en évidence de façon expérimentale, puis modélisé à l'aide d'un système de cinq équations couplées. Comme dans le cas de l'automodulation de phase, un outil de simulation a aussi été créé. D'autres effets, tels que la diffusion Raman stimulée ou l'amplification paramétrique ont également été étudiés de façon expérimentale.
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Baron, Alexandre. "Optique Non-Linéaire dans les structures semi-conductrices à fort confinement du champ." Phd thesis, Université Paris Sud - Paris XI, 2010. http://tel.archives-ouvertes.fr/tel-00573319.
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Du fait de leurs fortes propriétés non-linéaires, les structures photoniques semi-conductrices sont très intéressantes pour le traitement tout-optique du signal. La structuration à petite échelle permet de localiser la lumière et donc d'exalter les phénomènes non-linéaires, mais avec un pouvoir d'exaltation différent suivant l'ordre de la non-linéarité, introduisant ainsi une nouvelle hiérarchie des régimes d'interaction. Après une description théorique présentant le renforcement des processus non- linéaires par la localisation dans les semi-conducteurs, nous démontrons expérimentalement et quantitativement, pour la première fois, l'influence de la localisation sur l'exaltation des non- linéarités telles que l'effet Kerr, l'absorption à deux photons et les effets de porteurs libres, par l'étude d'un guide à cristal photonique de GaAs. Nous résolvons le problème de l'amplification Raman d'impulsions dans un nanoguide de silicium, en développant un modèle analytique permettant de montrer l'influence des effets de modulation de la phase non-linéaire sur la chute du gain Raman effectif dans le silicium. Ce modèle est validé expérimentalement. Finalement, nous abordons l'application de la localisation à la commutation non- linéaire tout-optique. Nous introduisons la notion de longueurs non-linéaire de commutation et d'absorption permettant d'étudier différents matériaux. Nous montrons que la commutation par effet Kerr pur est impossible pour le Si et le GaAs (contrairement à l'AlGaAs et au GaN), mais qu'une commutation par effet de porteurs libres y est envisageable pour certaines géométries de microstructures.
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"Silicon planar lightwave circuits: raman amplification and polarization processing." 2004. http://library.cuhk.edu.hk/record=b6073665.
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Liang Tak-keung."June 2004."
Thesis (Ph.D.)--Chinese University of Hong Kong, 2004.
Includes bibliographical references.
Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web.
Mode of access: World Wide Web.
Abstracts in English and Chinese.
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Wu, Jyun-Ming, and 巫俊明. "Observation of Raman Amplification on Integrated Silicon Microring Resonators." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/34661738750259139731.
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碩士國立清華大學
光電工程研究所
98
Raman amplifiers are important for optical communication because the power of signal gradually reduces along propagation. We must use amplifiers to recover signal power strong enough for defection. A Raman amplifier is one kind of amplifiers. The Raman coefficient in silicon is much higher than in fiber(10000 times) ,and it is a reason that we are interested using silicon waveguides to make a amplifier. The size of silicon Raman amplifiers is very small and can be integrated with other devices to accomplish many optical functions on a chip. In this thesis, we take advantage of high Raman coefficient in silicon and utilize resonant enhancement of microring resonators to make Raman amplifiers on silicon-on-insulator. In order to have better waveguide-fiber coupling, we use multimode waveguides and apply micro-electro-mechonical-system (MEMS) technology to allow waveguide and microring well coupled. In measurement, we observe spontaneous and stimulation Raman scattering by controlling the input power. When input power is higher, we also discover the free carrier effect affecting the signal power and refractive index of waveguide. However the loss of device is too high and we can’t adjust the power coupling ratio ,causing that Raman effect is not obvious. To improve the efficiency of device, we could use a novel low-loss silicon photonic wire to make our device in the future. The novel low-loss silicon photonic wire has advantages in low loss and single guide mode. So we expect that it can be better than multimode waveguide and maybe generates Raman laser.
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Shih, Wei-Tong, and 施威彤. "A Study of WDM Passive Optical Network with Raman Amplification." Thesis, 2008. http://ndltd.ncl.edu.tw/handle/hk4kca.
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碩士國立中山大學
光電工程研究所
96
Optical fiber access technology is the key to realize a broadband communication for everyone, and the passive optical network (PON) is enabling customers to enjoy high-speed internet access now. As the demand for the broadband access is still growing, a study to find out technologies to realize wider bandwidth for the access system is quite important. At this moment, wavelength division multiplexing (WDM) PON is the most promising technology for the future optical fiber access system. Current PON system covers a reach of within 20km from a central office, because the market of the access system is focusing on well-populated area. It is required to extend the reach of the PON system to enhance the applicable area, because there are many regions in the world where are not so highly populated. Therefore, this master thesis is focusing on to enhance the reach of the WDM-PON system. A little more specifically, a single fiber bidirectional 80 km WDM PON system with symmetric up-and-downstream data rate of 10.66Gb/s is reported. In order to enhance the reach of the WDM-PON system, Raman amplifier is utilized. As the Raman amplifier can amplify both directional optical signals simultaneously, it is quite effective to enhance the reach of the WDM-PON system. Even though, there are several effects that cause performance degradations of the system by introducing the Raman amplifier. It is important to clarify such effects and to provide solutions. This thesis discusses these issues also. One factor to degrade the system performance is the Rayleigh backscattering. As the Raman amplifier amplifies the Rayleigh backscattering, it interferes to the signal and causes the crosstalk penalty. At first, an experimental study has been conducted to clarify the significance of the Rayleigh backscattering, and the method to overcome the crosstalk penalty is presented. Then, another experiment to realize 80km WDM PON system with Raman amplifier is conducted, and it demonstrates a feasibility of such system. Finally, this thesis is concluded by a successful demonstration of the WDM-PON system with an enhanced reach.
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GAO, MIN-SHENG, and 高銘盛. "The study of Raman amplification in optical fiber communication system." Thesis, 1986. http://ndltd.ncl.edu.tw/handle/70080582942557217107.
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Drake, Philip, Y.-C. Chen, I. Lehmann, and P.-S. Jiang. "Nanoparticle labels for pathogen detection through nucleic acid amplification tests." 2014. http://hdl.handle.net/10454/10333.
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YesMagnetic nanoparticles and surface-enhanced Raman scattering (SERS) active nanoparticles were coated with short chain DNA tags. These were then used to identify a target bacterial DNA sequence. The tags function as primers in a standard PCR with the reverse primers and forward primers on the SERS nanoparticles and magnetic nanoparticles, respectively. During the PCR cycles, a composite nanostructure is formed that is both magnetically responsive and SERS active. After magnetic trapping, the intensity of the SERS signal can be related back to the concentration of the target DNA. A test assay was performed that showed a detection limit (based on the signal to noise ratio) of less than 3 zeptomole (41 pg/L). For comparison, a PCR assay based on the standard SYBR Green method was performed. This used the same primers and target DNA and had a detection limit of 10 attomoles (138 ng/L), 3,000 times less sensitive. The work documents the proof of principle study and shows for the first time the use of SERS-NP labels in the quantification of nucleic acid amplification tests and PCR.
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Sanders, James Christopher. "Terawatt Raman laser system for two-color laser plasma interactions." Thesis, 2014. http://hdl.handle.net/2152/26001.
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In some high-field laser-plasma experiments, it is advantageous to accompany the main high-energy (~1 J) laser with a second high-energy pulse (~0.1 J) which has been frequency-shifted by ~10-20%. Such a pulse-pair would have a low walk-off velocity while remaining spectrally distinct for use in two-color pump-probe experiments. Moreover, by shifting the second pulse by ~plasma frequency, it is theoretically possible to exercise some amount of control over a variety of laser-plasma instabilities, including forward Raman scattering, electromagnetic cascading, and relativistic self-focusing. Alternatively, the two pulses may be counter-propagated so that the collide in the plasma and create a slowly-propagating beatwave which can be used to inject electrons into a laser wakefield accelerator. The design, characeterization, and performance of a hybrid chirped-pulse Raman amplifier (CPRA)/Ti-Sapphire amplifier are reported and discussed. This hybrid system allows for the generation of a high-energy (>200 mJ), broadband (15-20 nm bandwidth FWHM), short duration (>100 fs duration) laser sideband. When amplified and compressed, the Raman beam's power exceeds 1 TW. This sideband is combined with the primary laser system to create a bi-color terawatt laser system which is capable of performing two-color high-field experiments. This two-color capability can be added to any commercial terawatt laser system without compromising the energy, duration or beam quality of the primary system. Preliminary two-color laser-plasma experiments are also discussed.text
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CHUNG, SUNG HAN. "Wavelength-Preserving Polarization-Insensitive All-Optical 3R Regenerator Based on Self- and Cross-Phase Modulation and Offset Filtering Utilizing Raman Amplification." Thesis, 2009. http://hdl.handle.net/1974/5278.
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Optical regeneration has the potential to significantly increase the reach of long-haul transmission systems. In this thesis, wavelength-preserving polarization-insensitive all-optical 3R regeneration is investigated and demonstrated for 10 and 40 Gb/s signals. The all-optical regenerator utilizes a self-pulsating laser for clock recovery, cross-phase modulation (XPM) based spectral broadening in a highly nonlinear fiber (HNLF) and offset filtering for retiming, and self-phase modulation based spectral broadening in a HNLF and offset filtering for reshaping. Raman amplification is used to increase the XPM-based spectral broadening and thus allow a design that meets the tradeoffs involved in simultaneously achieving good retiming and reshaping performance. The regenerator is shown to reduce amplitude noise and timing jitter while not causing a BER penalty. To fully validate the regeneration scheme, the cascadability is demonstrated using a recirculating loop. For a 10 Gb/s signal, with a regenerator spacing of 240 km, a return-to-zero, on-off-keyed (RZ-OOK) signal was transmitted over 18,000 km (75 loops) with a power penalty of 1.6 dB at a BER of 1E-9 compared to the back-to-back case. For a 40 Gb/s signal, with a regenerator spacing of 80 km, a RZ-OOK signal was transmitted over 8,000 km (100 loops) with a power penalty of 1.2 dB. In addition, all-optical 3R regeneration is demonstrated using a multimode quantum-dot Fabry Petot laser with ultra-low timing jitter.Thesis (Ph.D, Electrical & Computer Engineering) -- Queen's University, 2009-10-19 14:11:53.826
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Raghuwanshi, Sanjeev Kumar. "Analytical And Numerical Study Of Propagation In Optical Waveguides And Devices In Linear And Nonlinear Domains." Thesis, 2008. https://etd.iisc.ac.in/handle/2005/782.
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The objective of this thesis is to study of optical effects, arising in the form of non-uniform waveguide structure, complicated refractive index profiles or due to pulse propagation in dense wavelength division multiplexing (DWDM) optical communication systems. These effects are important and critically influence the performance of DWDM optical systems. A comprehensive survey of current literature on optical effects due to nonuniform optical structure and nonlinear optical effects is first done, showing their advantages and disadvantage in optical communication systems. A survey on methods of optical waveguide analysis is also done. The main contribution has been made to three main aspects of the problem :
Accurate analysis of uniform/non-uniform optical waveguides with arbitary refractive index profiles
Pulse propagation and distortion in DWDM Raman amplification systems.
Use of non-uniform FBG to compensate for pulse distortion
We study several existing analytical techniques developed so far for analyzing the mode of non-uniform optical waveguide structures. Later, we verify the analytical results by finite element method (FEM). The convergence study is also carried out. A new computational technique is proposed modifying the finite element method to analyze complex refractive index profiles required for the analysis, namely single mode step index profile, multi clad fiber, W -profile, chirp profile etc. An accuracy of 10−4 in the calculation of propagation constant/eigen-value is demonstrated. Dispersion characteristics of optical fibers w.r.t. different profile parameters is evaluated. A modification to scalar BPM is proposed and applied to study the effects of inhomogeneities along the propagation direction. The applicability and accuracy of the method is tested using integrated optic waveguide devices, namely, graded index slab waveguide. The proposed BPM uses Fourier decomposition of the transverse field. Coupled mode theory (CMT) of optical waveguides in non-homogeneous optical medium is applied to study the interaction of lightwaves propagation together such as in a DWDM system. The BPM results is verified by CMT.
The inhomogeneous waveguide theory is extended to study pulse propagation in DWDM optical communication system. Nonlinear optical effects are an important aspects of DWDM systems with fiber Raman amplifier. Finite difference time domain (FDTD) method is necessary to study these nonlinear optical effects as other conventional methods are not suitable here. Here, we discuss DWDM optical communication systems due to nonlinearity in the form of SRS effect. In case of FRA, we study the various kinds of fiber profile design parameters, for the purpose to achieve and extend the flat gain bandwidth over the EDFA window. We also propose and study, a new bi-directional optical fiber transmission scheme with various constraints, using Raman amplification process with and without pump depletion. Our scheme, provides an advantage like high SNR, low pump induced noise, for long-haul communication link. We find that, there is a quite significant crosstalk and power coupling among the dense DWDM channels but earlier discussed BPM fails to account for possible interference effects among the channels. To reduce the harmful nonlinear optical effects like four wave mixing (FWM), we need to deploy a high chromatic dispersion fiber, which will ultimately lead to high pulse walk-off rate among the DWDM channels; hence for high bit rate long haul systems, walk-off effect can not be ignored. Application of FDTD provided an improved insight into the effect of GVD on stimulated Raman scattering crosstalk than different modulation techniques and line codes. It is shown through analysis that pulse walk-off phenomena may distort the data asymmetrically; especially for case of wide-band DWDM transmission system. Hence, the pulse walk-off effect should be considered in future systems containing optical amplifier. It is shown, that large walk-off rate may reduce the crosstalk among DWDM channels but tends to increase the asymmetric pulse distortion. Data may lose due to high walk-off effect. We also investigate channel addition/removal process in DWDM fiber Raman amplifier. We also demonstrate that the pulse walk-off effect tends to lead significantly to positive chirp for higher frequency channels. This feature can be exploited to overcome the chromatic dispersion effects in DWDM transmission systems.
Pulse walk-off induced chirp, can be compensated by using the nonuniform fiber Bragg grating (NUFBG). The CMT due to periodic perturbation of the circular cylindrical waveguide structures is applied here. Here, we discuss the function of fiber Bragg grating as a transmission versus reflecting grating filter. We also discuss, FBG application to gain flattening of an EDFA window as well as how the group velocity dispersion (GVD) will be affected with bandwidth and coupling coefficient. We develop a new analytical technique to estimate the bandwidth of FBG based optical system. Finally, we investigate the dispersion compensation properties, pulse distortion, peak reflectivity analysis in uniform/non-uniform FBG due to an uniform/non-uniform incoming signal. More complicated refractive index profile can significantly reduce the GVD as well as side lobes intensity. Dispersion characteristic due to an arbitrary refractive index profile is discussed in details for the case of non-uniform FBG. Thus, we concluded that wide band DWDM optical communication system need to closely take into account various inhomogeneities and nonlinearities of optical fibers w.r.t. wave and pulse propagation.
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Raghuwanshi, Sanjeev Kumar. "Analytical And Numerical Study Of Propagation In Optical Waveguides And Devices In Linear And Nonlinear Domains." Thesis, 2008. http://hdl.handle.net/2005/782.
Full textAbstract:
The objective of this thesis is to study of optical effects, arising in the form of non-uniform waveguide structure, complicated refractive index profiles or due to pulse propagation in dense wavelength division multiplexing (DWDM) optical communication systems. These effects are important and critically influence the performance of DWDM optical systems. A comprehensive survey of current literature on optical effects due to nonuniform optical structure and nonlinear optical effects is first done, showing their advantages and disadvantage in optical communication systems. A survey on methods of optical waveguide analysis is also done. The main contribution has been made to three main aspects of the problem :
Accurate analysis of uniform/non-uniform optical waveguides with arbitary refractive index profiles
Pulse propagation and distortion in DWDM Raman amplification systems.
Use of non-uniform FBG to compensate for pulse distortion
We study several existing analytical techniques developed so far for analyzing the mode of non-uniform optical waveguide structures. Later, we verify the analytical results by finite element method (FEM). The convergence study is also carried out. A new computational technique is proposed modifying the finite element method to analyze complex refractive index profiles required for the analysis, namely single mode step index profile, multi clad fiber, W -profile, chirp profile etc. An accuracy of 10−4 in the calculation of propagation constant/eigen-value is demonstrated. Dispersion characteristics of optical fibers w.r.t. different profile parameters is evaluated. A modification to scalar BPM is proposed and applied to study the effects of inhomogeneities along the propagation direction. The applicability and accuracy of the method is tested using integrated optic waveguide devices, namely, graded index slab waveguide. The proposed BPM uses Fourier decomposition of the transverse field. Coupled mode theory (CMT) of optical waveguides in non-homogeneous optical medium is applied to study the interaction of lightwaves propagation together such as in a DWDM system. The BPM results is verified by CMT.
The inhomogeneous waveguide theory is extended to study pulse propagation in DWDM optical communication system. Nonlinear optical effects are an important aspects of DWDM systems with fiber Raman amplifier. Finite difference time domain (FDTD) method is necessary to study these nonlinear optical effects as other conventional methods are not suitable here. Here, we discuss DWDM optical communication systems due to nonlinearity in the form of SRS effect. In case of FRA, we study the various kinds of fiber profile design parameters, for the purpose to achieve and extend the flat gain bandwidth over the EDFA window. We also propose and study, a new bi-directional optical fiber transmission scheme with various constraints, using Raman amplification process with and without pump depletion. Our scheme, provides an advantage like high SNR, low pump induced noise, for long-haul communication link. We find that, there is a quite significant crosstalk and power coupling among the dense DWDM channels but earlier discussed BPM fails to account for possible interference effects among the channels. To reduce the harmful nonlinear optical effects like four wave mixing (FWM), we need to deploy a high chromatic dispersion fiber, which will ultimately lead to high pulse walk-off rate among the DWDM channels; hence for high bit rate long haul systems, walk-off effect can not be ignored. Application of FDTD provided an improved insight into the effect of GVD on stimulated Raman scattering crosstalk than different modulation techniques and line codes. It is shown through analysis that pulse walk-off phenomena may distort the data asymmetrically; especially for case of wide-band DWDM transmission system. Hence, the pulse walk-off effect should be considered in future systems containing optical amplifier. It is shown, that large walk-off rate may reduce the crosstalk among DWDM channels but tends to increase the asymmetric pulse distortion. Data may lose due to high walk-off effect. We also investigate channel addition/removal process in DWDM fiber Raman amplifier. We also demonstrate that the pulse walk-off effect tends to lead significantly to positive chirp for higher frequency channels. This feature can be exploited to overcome the chromatic dispersion effects in DWDM transmission systems.
Pulse walk-off induced chirp, can be compensated by using the nonuniform fiber Bragg grating (NUFBG). The CMT due to periodic perturbation of the circular cylindrical waveguide structures is applied here. Here, we discuss the function of fiber Bragg grating as a transmission versus reflecting grating filter. We also discuss, FBG application to gain flattening of an EDFA window as well as how the group velocity dispersion (GVD) will be affected with bandwidth and coupling coefficient. We develop a new analytical technique to estimate the bandwidth of FBG based optical system. Finally, we investigate the dispersion compensation properties, pulse distortion, peak reflectivity analysis in uniform/non-uniform FBG due to an uniform/non-uniform incoming signal. More complicated refractive index profile can significantly reduce the GVD as well as side lobes intensity. Dispersion characteristic due to an arbitrary refractive index profile is discussed in details for the case of non-uniform FBG. Thus, we concluded that wide band DWDM optical communication system need to closely take into account various inhomogeneities and nonlinearities of optical fibers w.r.t. wave and pulse propagation.
48
Nouroozi, Rahman [Verfasser]. "All optical wavelength conversion and parametric amplification in Ti: PPLN channel waveguides for telecommunication applications / von Rahman Nouroozi." 2010. http://d-nb.info/1010642960/34.
Full text