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Qiao, Jie. "Dense wavelength division multiplexing (DWDM) for optical networks." Access restricted to users with UT Austin EID, 2001. http://wwwlib.umi.com/cr/utexas/fullcit?p3035169.
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Taveira, Palmerston Donizzeti. "Caracterização e análise de desempenho dos amplificadores ópticos Raman discretos em sistemas de comunicações ópticas na banda O." Universidade Presbiteriana Mackenzie, 2006. http://tede.mackenzie.br/jspui/handle/tede/1414.
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Previous issue date: 2006-08-02The optical amplifier has improved the optical communication systems because they lead to an increase in transmission capacity of medium and long haul optical systems, with technological advantages over electronic regenerators. The optical amplifier are relatively simple to deploy and can be used in optical links without any troubles regarding signal transmission rate improvement and signal modulation changes, as a consequence of these issues they can substitute the electronic regenerator enhancing security with low operation cost. The CWDM systems multiplex optical wavelength with a low cost in metropolitan networks. It was developed to connect backbone networks to metro core and edge networks with cost saving over DWDM systems but lower transmission capacity. We have developed and characterized in our research a discrete Raman amplifier for operation in O band. We connected the amplifier in a point to point CWDM in order to analyze the gain on the system transmission capacity and the impairments that appears in the system. Working with a eight channel CWDM in O band, modulated with 2.5 Gbit/s, we have demonstrated that we can use a discrete Raman amplifier in single configurations, pre amplifier, booster and line amplifier and shared configuration with booster and pre amplifier to increase the transmission capacity that means, increase the length of the optical link. We have increased in 110% the length of the optical link with a shared configuration of two amplifiers with 10 dB gain for each one.
Os amplificadores ópticos revolucionaram a tecnológica das comunicações ópticas, pois possibilitaram o aumento da capacidade de transmissão dos sistemas ópticos de média e longa distância, com vantagens tecnológicas sobre os regeneradores. Estes dispositivos são relativamente simples de serem desenvolvidos, utilizam poucos componentes e podem ser utilizados nas redes ópticas de forma transparente a taxa de transmissão e modulação do sinal. Substituem assim, com vantagens, os regeneradores eletrônicos, agregando segurança e baixo custo à operação das redes ópticas. Os sistemas CWDM realizam a multiplexação óptica de comprimentos de onda a um baixo custo em redes metropolitanas. São utilizados para conectar as redes de transporte de alta capacidade às redes de acesso, trazendo uma larga vantagem em custo sobre os sistemas DWDM, porém com menor capacidade de transmissão. Nosso trabalho de pesquisa consistiu em desenvolver e caracterizar um amplificador Raman discreto na banda O (1260 a 1360 nm), aplicando este amplificador em um sistema CWDM ponto a ponto com taxa de transmissão de 2.5 Gbit/s por canal e analisando o aumento na capacidade de transmissão e os efeitos que degradam o sinal transmitido. Trabalhando com um sistema CWDM com oito canais na banda O, demonstramos que podemos utilizar um amplificador Raman discreto nas configurações isoladas de pré-amplificador, booster e amplificador de linha e na configuração simultânea de booster e pré-amplificador para aumentar a capacidade de transmissão. Aumentamos o comprimento original do enlace em 110%.
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Papageorgiou, Vasileios. "Techno-economic analysis of Open Optical LineSystems." Thesis, KTH, Skolan för elektroteknik och datavetenskap (EECS), 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-237414.
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Technology innovations and capacity upgrades in optical networks have influenced the optical transmission. As a result, network operators are considering separating hardware and software components in order to achieve efficiency and promising savings during network operation and network lifecycle. This leads to resolving the vendor lock-in and opening up the optical networks architectures such that different kinds of disaggregation models can be supported in the DWDM transport layer.In this master thesis, a techno-economic analysis which compares the economical differences between an integrated and disaggregated optical network has been conducted. For the analysis, an actual test case scenario of a European interregional network has been utilized. The line system and transponders components, price lists and features are based on actual vendor components in today’s optical transport networks.According to the results, it has been concluded that all total cost investments required for an integrated or disaggregated approach of DWDM system are traffic dependent. Moreover, capital expenses of open architecture are influenced by business model policy in price reduction due to multiple vendors’ competition on transponders. Calculations demonstrated that a disaggregated approach can introduce considerable total cost savings about 21% less total investments that include 25% less costs for capital expenses and 3% higher cost for operational expenses on an average traffic volume of European network. Finally, by increasing 5-10 times the traffic volume of European network it has been noticed that disaggregated system reduced total cost by 39% and 43% respectively.Tekniska innovationer och trafiktillväxt påverkar utvecklingen av optisk transmission. En konsekvens av detta är att nätoperatörer undersöker möjligheten att separera hårdvara och mjukvarukomponenter för öka effektiviteten och sänka kostnader för drift. Detta minskar inlåsning till enskilda leverantörer och öppnar upp dom optiska näten för att byggas med olika typer av disaggregering i DWDM transporten.I den här masteruppsatsen har en tekno-ekonomisk analys utförts avseende den ekonomiska skillnaden mellan integrerade och disaggregerade optiska nät. Ett verkligt nät scenario användes för analysen. Komponenter och kostnader för linjesystem och transpondrar är baserade på existerande system och prislistor i dagens nät. Enligt det erhållna resultatet har slutsatsen dragits att totala kostnaden för integrerade och öppna system är trafikberoende. Vidare så är investeringen för öppna system påverkad av pris reduktionen pga. konkurrens på transpondrar.Beräkningarna visar att disaggregerade system kan sänka kostnaderna med 21%, i dessa siffror ingår 25% lägre kostnad för investeringar och 3% högre driftkostnader.Slutligen, genom att öka trafikvolymen med 5 respektive 10 ggr från den ursprungliga trafik matrisen så kan de totala kostnaderna sänkas med 39% och 43%.
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Maamoun, Khaled M. "Deploying Monitoring Trails for Fault Localization in All-optical Networks and Radio-over-Fiber Passive Optical Networks." Thèse, Université d'Ottawa / University of Ottawa, 2012. http://hdl.handle.net/10393/23195.
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Fault localization is the process of realizing the true source of a failure from a set of collected failure notifications. Isolating failure recovery within the network optical domain is necessary to resolve alarm storm problems. The introduction of the monitoring trail (m-trail) has been proven to deliver better performance by employing monitoring resources in a form of optical trails - a monitoring framework that generalizes all the previously reported counterparts. In this dissertation, the m-trail design is explored and a focus is given to the analysis on using m-trails with established lightpaths to achieve fault localization. This process saves network resources by reducing the number of the m-trails required for fault localization and therefore the number of wavelengths used in the network. A novel approach based on Geographic Midpoint Technique, an adapted version of the Chinese Postman’s Problem (CPP) solution and an adapted version of the Traveling Salesman’s Problem (TSP) solution algorithms is introduced. The desirable features of network architectures and the enabling of innovative technologies for delivering future millimeter-waveband (mm-WB) Radio-over-Fiber (RoF) systems for wireless services integrated in a Dense Wavelength Division Multiplexing (DWDM) is proposed in this dissertation. For the conceptual illustration, a DWDM RoF system with channel spacing of 12.5 GHz is considered. The mm-WB Radio Frequency (RF) signal is obtained at each Optical Network Unit (ONU) by simultaneously using optical heterodyning photo detection between two optical carriers. The generated RF modulated signal has a frequency of 12.5 GHz. This RoF system is easy, cost-effective, resistant to laser phase noise and also reduces maintenance needs, in principle. A revision of related RoF network proposals and experiments is also included. A number of models for Passive Optical Networks (PON)/ RoF-PON that combine both innovative and existing ideas along with a number of solutions for m-trail design problem of these models are proposed. The comparison between these models uses the expected survivability function which proved that these models are liable to be implemented in the new and existing PON/ RoF-PON systems. This dissertation is followed by recommendation of possible directions for future research in this area.
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Grenar, David. "Řešení nasazení DWDM systémů na 100G a 400G." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2016. http://www.nusl.cz/ntk/nusl-242064.
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The aim of this master´s thesis is an explanation of the problem of transport optical networks with Dense Wavelength Division Multiplexing. DWDM principle, properties and limit of transmission system. Focus of thesis is also specification properties of migration transmission system to higher speed 40G, 100G and in future to 400G. Part of thesis is outlined the basic division of multiplexing system, there are discussed the basic solutions of wavelength multiplexes CWDM and DWDM, focus for the effects of nonlinear phenomena and parasitic modulation FWM, SPM and XPM in modulation DP-QPSK and 16-QAM. In practicle part we will make measurement of properties of 10G and then experimental measurement parameters on 100G.
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Lepley, Jason J. "Frequency stabilisation for dense wavelength division multiplexing systems." Thesis, University of Essex, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.310059.
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Thomas-Dupuis, Frédéric. "Investigation of two-dimensional optical formatting for dense wavelength division multiplexing." Thesis, McGill University, 2002. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=79265.
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Many multi-channel free-space micro-optical components such as micro-mirror switches and (tunable) vertical-cavity surface emitting lasers (VCSELs) are arranged in two-dimensional arrays. This thesis explores the design, implementation and characterization of a two-dimensional optical wavelength (de)multiplexer designed to interface between wavelength division multiplexing (WDM) optical networks and 2D micro-mirror optical switch, VCSEL or detector arrays. The system uses multifacet gratings to map the light from a traditional optical (de)multiplexer to a 4 x 16 array with a pitch of 250 mum. The device is 6.05 mm in length and could be fabricated by plastic injection molding. The device successfully performs the two-dimensional mapping. The average efficiency for the device was measured to be 10.4%. The thesis ends with a list of future work that can be done to improve both the theoretical and practical efficiency of the device.
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Boeck, Robert. "High performance silicon photonic filters for dense wavelength-division multiplexing applications." Thesis, University of British Columbia, 2016. http://hdl.handle.net/2429/57688.
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This dissertation presents theoretical and experimental results for silicon optical ring resonator filters that meet many of the typical commercial specifications for dense wavelength-division multiplexing (DWDM) filters. First, we theoretically demonstrate a silicon quadruple Vernier racetrack resonator that meets 4-port filter commercial specifications for a clear window of 0.08 nm and a channel spacing of 0.8 nm while being tolerant to typical fabrication variations. Next, we experimentally demonstrate a silicon quadruple Vernier racetrack resonator that meets many 3-port filter commercial specifications for a clear window of 0.048 nm and a channel spacing of 0.8 nm. Then, enhanced resonant tuning range using the Vernier effect is theoretically and experimentally demonstrated using a thermally tunable silicon quadruple Vernier racetrack resonator. Also, we sent 12.5 Gbps data through a thermally tunable silicon quadruple Vernier racetrack resonator and show open eye diagrams in both the drop port and through port of the filter, even within one of the minor through port notches. We then present theoretical and experimental results on a high performance silicon double microring resonator filter using Mach-Zhender interferometer-based coupling that meets numerous 3-port filter commercial specifications for a clear window of 8 GHz and a channel spacing of 200 GHz as well as having an FSR larger than the span of the C-band and low through port passband dispersion. Next, we present a FSR-eliminated silicon Vernier racetrack resonator filter. We demonstrate the performance of this filter both theoretically and experimentally. The FSR of this filter is eliminated by using contra-directional grating couplers (contra-DCs) to suppress all but one of the notches and peaks of the filter's spectra. Lastly, a process calibration procedure is demonstrated that accurately determines the coupling coefficients of fabricated contra-DCs and is used to design a FSR-eliminated silicon Vernier racetrack resonator filter that meets 3-port filter commercial specifications for a clear window of 13 GHz and a channel spacing of 200 GHz. This filter also has low drop port dispersion and low dispersion within the passbands of the through port.Applied Science, Faculty of
Electrical and Computer Engineering, Department of
Graduate
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Zhu, Jiannan. "Novel energy-efficient DWDM systems for low-cost optical communication applications." Thesis, University of Cambridge, 2015. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.709467.
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Akanbi, Oladeji Bamidele. "Bi-directional Dense Wavelength Division Multiplexed Systems for Broadband Access Networks." Diss., Georgia Institute of Technology, 2006. http://hdl.handle.net/1853/13964.
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Dense wavelength division multiplexing (DWDM) is becoming the technology of choice for meeting the increasing bandwidth demands in optical networks. DWDM has been used to increase the capacity of long-haul optical transport systems. Efforts are being made to move DWDM into the broadband access network serving residential and business subscribers.
First, a new centralized DWDM PON scheme is demonstrated for bi-directional upstream and downstream transmissions. The proposed DWDM PON scheme is implemented using optical carrier suppression and separation (OCSS) technology to generate a wavelength pair from a single laser source at the central office. This method enables the co-location of both upstream and downstream DWDM transmitters in the central office. In addition, the complexity, cost, and maintenance of the optical network unit are reduced by enabling wavelength independent operation.
Second, a new multistage architecture is proposed for the delivery of information to groups of subscribers located at different distances from the central office. A 25 GHz DWDM comb is generated using OCSS technology, and error-free transmission of four 10 Gbps channels is demonstrated.
Finally, a new wide area access network with bi-directional DWDM amplification using semiconductor optical amplifiers (SOAs) is demonstrated. The detrimental effect of SOA
crosstalk resulting from cross gain modulation can be suppressed using a constant intensity
modulation format such as differential phase shift keying (DPSK). The feasibiity of
bi-directional DPSK transmission of 16
interleaved DWDM channels using an in-line SOA has been studied experimentally. In addition, the reduction of bi-directional SOA reflections has been realized by optimizing the SOA bias current and facet reflectivities.
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Al-Fuqaha, Ala Isam Chaudhry Ghulam M. "Routing and wavelength assignment in all-optical DWDM networks with sparse wavelength conversion capabilities." Diss., UMK access, 2004.
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Thesis (Ph. D.)--School of Computing and Engineering. University of Missouri--Kansas City, 2004."A dissertation in engineering and computer networking." Advisor: Ghulam Chaudhry. Typescript. Vita. Title from "catalog record" of the print edition Description based on contents viewed Feb. 22, 2006. Includes bibliographical references (leaves 135-157). Online version of the print edition.
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Youssef, Ahmed H. "ASSESSMENT OF PHOTONIC SWITCHES AS FUTURE REPLACEMENT FOR ELECTRONIC CROSS-CONNECT SWITCHES." International Foundation for Telemetering, 1999. http://hdl.handle.net/10150/608526.
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International Telemetering Conference Proceedings / October 25-28, 1999 / Riviera Hotel and Convention Center, Las Vegas, NevadaThis paper presents the future of optical networking via photonic switches as a potential replacement for the existing electronic cross-connects. Although optical amplifiers are now mainstream and wave division multiplexing (WDM) systems are a commercial reality, the industry’s long-term vision is one of the all-optical network. This will require optical switching equipment such as all-optical or “photonic” cross-connect switches that will provide packet switching at an optical layer. Currently, as voice calls or data traffic are routed throughout Range and commercial networks, the information can travel through many fiber-optic segments which are linked together using electronic cross-connects. However, this electronic portion of the network is the bottleneck that is preventing the ideal network from achieving optimal speeds. Information is converted from light into an electronic signal, routed to the next circuit pathway, then converted back into light as it travels to the next network destination. In an all-optical network, the electronics are removed from the equation, eliminating the need to convert the signals and thereby significantly improving network performance and throughput. Removing the electronics improves network reliability and restoration speeds in the event of an outage, provides greater flexibility in network provisioning, and provides a smooth transition when migrating to future optical transmission technologies. Despite the fact that photonic switching remains uncommercialized, it now seems apparent that the core switches in both the public networks and DoD Range networks of the early 21st century will probably carry ATM cells over a photonic switching fabric.
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Abou-Galala, Feras Moustafa. "True-time all optical performance monitoring by means of optical correlation." Columbus, Ohio : Ohio State University, 2007. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1180549555.
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Song, Jun. "Electromagnetic simulation and design of etched diffraction grating demultiplexers." Doctoral thesis, KTH, Elektroteknisk teori och konstruktion, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-4791.
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Among various planar lightwave circuits for multiplexing/demultiplexing in an optical communication system, etched diffraction gratings (EDGs) have shown great potential due to their compactness and high spectral finesse. Conventional numerical methods for grating simulation cannot be used to simulate an EDG demultiplexer of large size (in terms of the wavelength). In the present thesis, the polarization-dependent characteristics of an EDG demultiplexer are analyzed with a boundary element method (BEM) for both an echelle grating coated with a metal and a dielectric grating with total internal reflection (TIR) facets. For EDGs with metal-coated facets, we use a more effective method, namely, method of moments (MoM). Futhermore, a fast simulation method for EDGs with TIR facets is presented based on the Kirchhoff–Huygens principle and the Goos-Hänchen shift. This simple method has a good agreement with a BEM over a wide range of practical parameters of the device. Several novel designs are presented in order to improve the performances of EDGs. (1) By making some appropriate roughness on the surface of the shaded facets, the PDL of the demultiplexer can be effectively reduced over a large bandwith. (2) For EDGs based on Si nanowire structures, we compensate the polarization-dependent wavelength dispersion (PDλ) in the whole operational spectrum by introducing a polarization compensation area in its free propagation region. (3) An EDG demultiplexer with suppressed sidelobe is designed. The designed EDG demultiplexer can give a crosstalk as small as 50 dB in theory. (4) By chirping the diffraction order for each facet, we minimize the envelope intensity for the other adjacent diffraction orders to achieve a negligible return loss in a large spectral width. (5) A design for EDG demultiplexers is presented to obtain both large grating facets and a larger free spectral range (FSR) using the optimal chirped diffraction orders for different facets. The influences of the fabrication errors (e.g., rounded effect, surface roughness and point defect in the waveguide) on the performance (such as the insertion loss, the polarization dependent loss and the chromatic dispersion) of an EDG demultiplexer are also analyzed in detail. Silicon nanowire waveguides and related EDGs are studied. An EDG demultiplexer with 10 nm spacing is finally fabricated and characterized.QC 20100910
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Chen, Xin. "Energy efficient wired networking." Thesis, Queen Mary, University of London, 2015. http://qmro.qmul.ac.uk/xmlui/handle/123456789/7966.
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This research proposes a new dynamic energy management framework for a backbone Internet Protocol over Dense Wavelength Division Multiplexing (IP over DWDM) network. Maintaining the logical IP-layer topology is a key constraint of our architecture whilst saving energy by infrastructure sleeping and virtual router migration. The traffic demand in a Tier 2/3 network typically has a regular diurnal pattern based on people‟s activities, which is high in working hours and much lighter during hours associated with sleep. When the traffic demand is light, virtual router instances can be consolidated to a smaller set of physical platforms and the unneeded physical platforms can be put to sleep to save energy. As the traffic demand increases the sleeping physical platforms can be re-awoken in order to host virtual router instances and so maintain quality of service. Since the IP-layer topology remains unchanged throughout virtual router migration in our framework, there is no network disruption or discontinuities when the physical platforms enter or leave hibernation. However, this migration places extra demands on the optical layer as additional connections are needed to preserve the logical IP-layer topology whilst forwarding traffic to the new virtual router location. Consequently, dynamic optical connection management is needed for the new framework. Two important issues are considered in the framework, i.e. when to trigger the virtual router migration and where to move virtual router instances to? For the first issue, a reactive mechanism is used to trigger the virtual router migration by monitoring the network state. Then, a new evolutionary-based algorithm called VRM_MOEA is proposed for solving the destination physical platform selection problem, which chooses the appropriate location of virtual router instances as traffic demand varies. A novel hybrid simulation platform is developed to measure the performance of new framework, which is able to capture the functionality of the optical layer, the IP layer data-path and the IP/optical control plane. Simulation results show that the performance of network energy saving depends on many factors, such as network topology, quiet and busy thresholds, and traffic load; however, savings of around 30% are possible with typical medium-sized network topologies.
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Hsu, Sheng-Hao, and 徐聲豪. "Temperature and Stresses Effects on The Central Wavelength Shifting of Dense-Wavelength-Division-Multiplexing (DWDM) Filters." Thesis, 2008. http://ndltd.ncl.edu.tw/handle/34337500368355970179.
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碩士國立中央大學
光電科學研究所
96
Dense-wavelength-division-multiplexing (DWDM) filter is a kind of very important component for optical fiber communication. Since any tiny wavelength shift will make the filter ineffective. The temperature shift of central wavelength (TSCW) of DWDM filters has to be limited less than 1pm/oC based on the Bellcore GR-2883 standard. The TSCW of filters are depended on the mechanical properties of the stress. Takashashi was the first one to construct the theoretical model of TSCW using the Elastic Strain model in 1995. This model based on the Stoney’s equation showed that the most important parameters are CTE of the substrate and the film, besides the refractive index, Young’s modulus, Poisson ratio, the normalized temperature coefficient of refractive index (NTCRI) of the film are important too. However, when the thickness ratio of the substrate and the film is larger than 1%, the Stoney’s equation should be modified. Using the modified Stoney’s equation the CTE of the DWDM filter about 0.87 ppm/oC have been achieved. Then measured the TSCWs of different sizes and substrates of DWDM filters, we can achieve other parameters, the biaxial modulus, 41 GPa; the Poisson ratio, 0.22; the temperature coefficient of refractive index, 1.4×10-5/oC; and the stress-optic coefficient, -1.9×10-12 /Pa. With all the parameters we can predict the TSCWs of the different DWDM filters.
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Kuo, Chien-Cheng, and 郭倩丞. "Research of the Stresses and Thermal Stabilities in the Dense-Wavelength-Division-Multiplexing (DWDM) Filters." Thesis, 2007. http://ndltd.ncl.edu.tw/handle/06109862936312967843.
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博士國立中央大學
光電科學研究所
95
Dense-wavelength-division-multiplexing (DWDM)filter is a very important component for optical fiber communication. DWDM filter fabricated by thin film coating is a type of narrow bandpass filter (NBPF). The stability and reliability of these applications are depended on the mechanical properties of the stresses, the Young’s modulus, Poisson ratio, Temperature coefficient of refractive index and the Coefficients of Thermal Expansion (CTE) of the thin films and their substrates. However if the substrate thicknesses were changed, the mechanical and optical properties of the thin films are also changed. Takashashi is first one to offer the theory model for the temperature stability of the center wavelength (TSCW). But the request for the optic fiber communication system is more difficult, the thickness of the DWDM filters increase. We must consider the effect of the stress changes on the DWDM filters. In this paper we provide new formula to analyze the influence of the stresses and thermal stabilities in the Dense-Wavelength-Division-Multiplexing (DWDM) filters and compare the influence of Coefficients of Thermal Expansion (CTE) of the substrate, the Young’s modulus of thin film, Poisson ratio of thin film, Temperature coefficient of refractive index of thin film and the Coefficients of Thermal Expansion (CTE) of the thin films in real 100GHz filter result. We have more understanding to the influence of stress and temperature of the DWDM filters and can apply to the filters of thick thin film thickness or thin substrate. We can predict the change on the optics characteristic that the stress and temperature cause.
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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.
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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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wu, Chi-Shou, and 吳啟守. "A Dense Wavelength Division Multiplexing Scheme using Wavelength Multiplexing in Photorefractive Volume Holography." Thesis, 2002. http://ndltd.ncl.edu.tw/handle/39378018339086734494.
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碩士中原大學
應用物理研究所
90
Dense-wavelength division multiplexing (DWDM) is an important scheme for increasing communication capacity in fiber optic communication. There are various approaches for implementing DWDM and each approach has its advantages and disadvantages. A successful DWDM should have a large number of channels (for which a narrow 3-dB bandwidth or channel spacing is needed), and environmental resilience. Since volume holography has been used in information storage with various multiplexing schemes, including angular, wavelength, and phase multiplexing, for increasing the storage capacity, it is easy to conclude that there is a potential application of volume holography in DWDM. Since the grating period in a typical reflection hologram is much smaller than that of a transmission hologram, a reflection hologram can result in a larger storage capacity than that of a transmission hologram. The information storage capacity of a volume hologram is determined by its Bragg selectivity. There are various approaches for calculating this selectivity, which includes the Coupled Wave Theory, Born’s Approximation, and recently, the Phase Summation Method. Since the Coupled Wave Theory can take into account both linear and nonlinear interaction between the incident light and the hologram grating, the Bragg selectivity derived from this theory represents the most accurate result. However, it provides no formula for predicting either the HWFZ (half width at first zero) or the FWHM (full width at half maximum), which is essential for designing appropriate bandwidth in DWDM. This thesis has verified that the Bragg selectivity calculated by using the Phase Summation Method in the regime of low diffraction efficiency is the same as that of Coupled Wave Theory. This thesis is the first to derive a formula for calculating HWFZ for the Bragg selectivity of reflection hologram using the Phase Summation Method. This thesis also proposes a DWDM scheme using volume holography and is the first to establish a unique design protocol for DWDM using a reflection hologram as detailed below. However, the HWFZ for each center wavelength increases as the wavelength increases. In order to make the bandwidth of each center wavelength must be equal. This thesis is the first to propose an innovative approach to combine both angular multiplexing with wavelength multiplexing in order to keep the bandwidth constant within the S, C, and L band of the fiber transmission window. Using the above results, this thesis has provided a DWDM design, which consists of 2048 channels and a channel spacing of 0.05nm using a photorefractive crystal of LiNbO3 and reflection holography. Keywords：Dense wavelength division multiplexing, fiber optic communication, Photorefraction, reflection hologram, volume holography, angular multiplexing, wavelength multiplexing, LiNbO3
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Tupakula, Sreenivasulu. "Photonic Crystal Ring Resonators for Optical Networking and Sensing Applications." Thesis, 2016. http://etd.iisc.ernet.in/handle/2005/2860.
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Photonic bandgap structures have provided promising platform for miniaturization of modern integrated optical devices. In this thesis, a photonic crystal based ring resonator (PCRR) is proposed and optimized to exhibit high quality factor. Also, force sensing application of the optimized PC ring resonator and Dense Wavelength Division Multiplexing (DWDM) application of the PCRR are discussed. Finally fabrication and characterization of the PCRR is presented.
A photonic crystal ring resonator is designed in a hexagonal lattice of air holes on a silicon slab. A novel approach is used to optimize PCRR to achieve high quality factor. The numerical analysis of the optimized photonic crystal ring resonator is presented in detail. For all electromagnetic computations Finite Difference Time Domain (FDTD) method is used.
The improvement in Q factor is explained by using the physical phenomenon, multipole cancellation of the radiation held of the PCRR cavity. The corresponding mathematical frame work has been included. The forced cancellation of lower order radiation components are verified by plotting far held radiation pattern of the PCRR cavity.
Then, the force sensing application of the optimized PCRR is presented. A high sensitive force sensor based on photonic crystal ring resonator integrated with silicon micro cantilever is presented. The design and modelling of the device, including the mechanics of the cantilever, FEM (Finite Element Method) analysis of the cantilever beam with PC and without PC integrated on it. The force sensing characteristics are presented for forces in the range of 0 to 1 N. For forces which are in the range of few tens of N, a force sensor with bilayer cantilever is considered. PC ring resonator on the bilayer of 220nm thick silicon and 600nm thick SiO2 plays the role of sensing element. Force sensing characteristics of the bilayer cantilever for forces in the range of 0 to 10 N are presented.
Fabrication and characterization of PCRR is also carried out. This experimental work is done mainly to understand practical issues in study of photonic crystal ring resonators. It is proved that Q factor of PCRR can be signi cantly improved by varying the PCRR parameters by the proposed method.
Dense Wavelength Division Multiplexing (DWDM) application of PC ring resonator is included. A novel 4-channel PC based demultiplexer is proposed and optimized in order to tolerate the fabrication errors and exhibit optimal cross talk, coupling efficiency between resonator and various channels of the device. Since the intention of this design is, to achieve the device performance that is independent of the unavoidable fabrication errors, the tolerance studies are made on the performance of the device towards the fabrication errors in the dimension of various related parameters.
In conclusion we summarize major results, applications including computations and practical measurements of this work and suggest future work that may be carried out later.
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Viljoen, Peter Martin. "Improving DWDM transmission systems by using dispersion management." Thesis, 2012. http://hdl.handle.net/10210/8238.
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M.Ing.In this dissertation the emphasis falls on the use of the 1550 run WDM systems that make use of standard single-mode fibre. The reason for this is that more than 50 million kilometres of standard telecommunication fibre is already installed in the worldwide telephone network. Therefore, from an economical point of view, the fourth generation of lightwave systems has to make use of this existing base. Using single-mode fibre at high bit-rate (- 10 Gb/s) dispersion becomes a problem. Furthermore, if amplifiers are used, as in the case of long-haul WDM systems, non-linear effects also become important although the input power levels are low (-1 mW). Thus, the system performance is influenced by both the dispersion problem and fibre non-linearities. In this dissertation the influence of these effects was investigated and the use of different dispersion management schemes was considered in order to minimise the dispersion and the effects of these non-linearities on the optical signals. It was seen that by using pre-compensation, the optical pulses would become narrower whereas by using post-compensation, the pulses would be broader than the original input pulses. Thus, the combined effect of fibre non-linearity and fibre dispersion led to the fact that the order in which dispersion compensation is realised is important. By using symmetrical dispersion compensation that is defined as a dispersion compensation scheme that makes use of an equal amount of pre- and post-compensation sections, the tendency of pulse narrowing and pulse broadening can be balanced. It was found from simulations, that pre-compensation led to a smaller SPM penalty than postcompensation, whereas in the case of cross-phase ,modulation, the opposite is true. Using lumped dispersion compensation at the,en(f:o£ the system, it was found that both SPM and XPM penalties could be minimised. It was found that negative and positive lumped dispersion compensation could be used to improve the system perfortriance of pre- and post compensation schemes respectively. The performance of symmetrical compensation also improved by using a positive lumped dispersion compensation regarding SPM penalty, but in the case of XPM penalty, it was found that lumped dispersion compensation could not be used to improve this penalty. Furthermore, the effect of not using 100% dispersion compensation per span on the system performance was determined. From simulations, it followed that under-compensation will lead to an improvement in the system performances of the post- and symmetrical dispersion compensation, whereas an over-compensation will lead to an improvement in the precompensation case. It was also shown that XPM index penalty decreases in all of these dispersion compensation schemes if 100% compensation per span is not used. The reason for this is the inter -span walk-off that reduces the XPM distortion by reducing the localised buildup of phase distortions. Finally, it was shown that by independently controlling the input power levels in the SMF and DCF the best system performance is possible. Furthermore, by making use of lumped dispersion compensation or by not using 100% dispersion compensation per span, the system performance of the pre-, post- and symmetrical dispersion conipensation schemes can be improved quite a lot. Comparing the results of the pre-, post- and symmetrical dispersion compensation schemes that made use of independent control of power levels with the pre-, post- and symmetrical dispersion compensation schemes that did not use independent control ofpower levels, the Q factors were improved from 6.2 to 8, from 5.4 to 9 and from 7.5 to 11 in each case respectively.
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Hsieh, chengyu, and 謝鎮宇. "All-Optical Multicast in Dense Wavelength Division Multiplexing Networks." Thesis, 2002. http://ndltd.ncl.edu.tw/handle/13837958194027628615.
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碩士國立臺灣大學
電機工程學研究所
90
This thesis studies all-optical multicast routing in wavelength-routed optical networks with sparse light splitting. In a sparse splitting network, only a small percentage of nodes are capable of light splitting, i.e., multicast capable, and the rest are multicast incapable. The typical solutions of existing multicast routing algorithms for sparse splitting networks combine an existing Steiner Tree heuristics with some rerouting procedures to refine the trees. The resulting tree cost in terms of the total number of wavelengths used on all tree links (i.e., wavelength channel cost) is then very expensive. In this thesis, we propose a new mechanism that constructs all-optical light-trees for sparse splitting networks without an additional rerouting procedure in the tree construction. We suggest two efficient approaches to grow a light-tree for a given multicast session in which the tree cost is minimized, and extend our mechanism to support dynamic group membership in the network. Their performances are evaluated by estimating their worst-case bound. The result shows that the suboptimal solution generated by our approach is within triple of the optimal one. Also, an extensive simulation is conducted to compare the performance of our mechanism with existing work. The results show that our mechanism builds light-trees with the least wavelength channel cost and with the smallest number of wavelengths used per link.
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Yin, Chien-Tsen, and 尹介岑. "The Implementation of Dense Wavelength Division Multiplexing Fiber Gratings." Thesis, 2004. http://ndltd.ncl.edu.tw/handle/03195135463808054584.
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碩士逢甲大學
電機工程所
92
Since the bandwidth of website is needed to increase greatly for satisfying the speed-rate-data transmission, Dense Wavelength Division Multiplexing (DWDM) systems can solve this problem. In an DWDM system, the fiber Bragg grating can act as key component for extracting the optical signal. The content of thesis is to design and fabricate 50GHz and 100GHz fiber gratings DWDM systems. Because fiber gratings have low insertion loss, low polarization dependent loss, better wavelength selectivity, and narrow bandwidth with for high channel isolation. By means of phase mask writing technique and controlling grating -exposed time, we implement the fabrication of 50GHz and 100GHz fiber gratings. To fabricate 50GHz and 100GHz fiber gratings of ITU (International Telecommunication Union) specification, the index modulation of fiber core should be the gauss distribution with the constant average index. This component can be applied to the different channel space of optical add/drop filters.
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Xiao-Hang, Zhang, and 張曉航. "Research in "Dense Wavelength Division Multiplexing" Optic Fiber Communication System." Thesis, 2002. http://ndltd.ncl.edu.tw/handle/26642254784261233704.
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碩士國防大學中正理工學院
應用物理研究所
90
Because of the properties of high speed and capacity, low cost and loss, free from electromagnetic interference, and privacy protected efficiently, fiber optics is becoming a new star in wired communication systems. Today, as demand for faster data transfer speeds soars, traditional fiber optics systems, which have their own limitations fail to meet the need. The scientists have to seek new technologies for increasing the transmissive ability of fiber optic communication system. There are two key technical developments that are pushing it forward: one is the Impulse Bandwidth and the other is “wavelength division multiplexing”; the latter is the focus of this dissertation. “Dense wavelength division multiplexing” (DWDM) is a main stream to develop wavelength division multiplexing for the future. It is to narrow down the channel interval (less than 2 nm), so the current fiber optics can transmit wave band in maximum capacity. The studying methods of this dissertation are to search and collect articles related to DWDM, understand the recent technological developments, discuss and confront the probably problems that DWDM might occur, and then analyze them and compare with every possible solutions in order to catch on the evolution in the future.
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Su, Chin Feng, and 蘇晉鋒. "Gain Flattening of EDFA for Dense Wavelength Division Multiplexing optical communications." Thesis, 2002. http://ndltd.ncl.edu.tw/handle/90096572071390093260.
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Wu, Chun-Lung, and 吳俊龍. "Studies of long reach dense wavelength division multiplexing passive optical networks." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/65194828430912207413.
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碩士國立交通大學
光電工程學系
98
In this thesis, we proposed and investigated a Rayleigh backscattering (RB) noise mitigation scheme by using single sideband non-return-to-zero (CS-SSB-NRZ) signal generated by a dual-parallel Mach-Zehnder modulator (DP-MZM) based colorless optical networking unit (ONU). A brief introduction and review of different Long reach passive optical networks (LR-PONs) are given in chapter 1 and chapter 2 respectively. Detail analysis of the CS-SSB-NRZ generation is shown in chapter 3. We analyzed the RB tolerances of the NRZ and the CS-SSB-NRZ signals, and demonstrated two architectures of LR-PONs with centralized light source (CLS) in chapter 4 and chapter 5 respectively. One architecture of the LR-PON can reach 100 km. A high split-ratio of 512 is achieved using 10 Gb/s downstream and 2.5 Gb/s upstream signals. In chapter 6, we calculated the power consumption per customer in the proposed LR-PON. The result shows that LR-PON is more power-efficient than conventional PON, ADSL and FTTN. In chapter 7, a conclusion and proposed future works are given.
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Chen, Yen-chang, and 陳彥彰. "Original Design of Dense Wavelength Division Multiplexing Filter as to the Optical efficiency." Thesis, 2008. http://ndltd.ncl.edu.tw/handle/35959758028368117542.
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碩士國立成功大學
奈米科技暨微系統工程研究所
96
This paper has three parts to investigate DWDM narrow bandpass filter.The first part provides two methods to reduce the total number of layers. One method is combining solid etalon filter and dielectric multilayer filter by optical contact is one method; the other method is to combine two dielectric multilayer filters by optical contact. The second part provides a way to modify the central wavelength for solid etalon filter by using low refractive index material. Formula used to calculate the thickness of the low refractive material was derived. The third part provides a way to reduce the ripple affection by using Cushing’s technique together with addressing some technique to calculate the thickness of high and low refractive index material.
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Lee, Chien-Tsung, and 李建宗. "Applications and Analysis of Apodized Fiber Gratings For Dense Wavelength-Division Multiplexing Fiber Communications." Thesis, 2006. http://ndltd.ncl.edu.tw/handle/7m57dn.
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碩士國立臺北科技大學
電機工程系所
94
Characterization and analysis of apodized, including both uniform and chirped, fiber gratings were investigated in this work. For the optical filtering in the dense wavelength-division multiplexing (DWDM) systems, apodized gratings with different channel spacings of 100G, 50G, 25GHz were designed, using inverse processes, to meet the specific requirements set up by International Telecommunication Union. The best gratings obtained for the above channel spacings exhibit improved sidelobe suppressions of 112.8 dB, 84.2 dB, and 53.1 dB, in their Bragg reflectivity spectra, respectively. Moreover, it was found that the magnititude of time-delay variation of the optical signal pulse would strongly affect system performance, particularly for high-bit rate transmissions. A new sort of the apodized chirped fiber Bragg gratings (ACFBG) was found. This grating structure provided best dispersion compensation, compared to other work, resulting from the above time delay variation. Using this grating for dispersion compensation, take the 40Gb/s system for example, the best compensation distance is 140 km, power penalty is 0.3 dB, Eye-opening penalty is 10.0 dB, Bit error rate is 3.53E-10 and signal restoration rate is 1.6. To the best of our knowledge, this ACFBG can provide superior system performance to those of other work.
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Zou, Jizuo Chen Ray T. "High performance dense wavelength division multiplexing/demultiplexing based on blazed grating and ion-exchanged glass waveguide technique." 2004. http://repositories.lib.utexas.edu/bitstream/handle/2152/2109/zouj042.pdf.
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Zou, Jizuo. "High performance dense wavelength division multiplexing/demultiplexing based on blazed grating and ion-exchanged glass waveguide technique." Thesis, 2004. http://hdl.handle.net/2152/2109.
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Hsieh, Chao-Shing, and 謝昭行. "Fabrication of Flat-Top Interleaver and Add/Drop Filter Modules in Dense Wavelength Division Multiplexing System." Thesis, 2003. http://ndltd.ncl.edu.tw/handle/30065212956007266384.
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博士國立中山大學
光電工程研究所
91
In this dissertation, we study the fabrication and performance of fiber coupler, add/drop filter module, and flat-top interleaver for use in dense wavelength division multiplexing (DWDM) systems. In the low loss fused biconical taper coupler (FBTC), an optimum approach for fabrication of FBTC is a lower filament speed, a higher gas flow rate, and a longer pulling length. By applying this optimum approach that the FBTCs with low loss of 0.13 dB and small taper angle of 20o have been fabricated successfully. In the add/drop filter module, the module-insertion loss difference (0.3 dB) and angular tilt misalignment (0.05o) are found after undergoing 42 temperature cycles for the imperfect soldering process. We present our experimental results of a flat-top 50 GHz optical interleaver using two Gires-Tournois Etalons (GTEs) as phase dispersive mirrors in a Michelson interferometer. The spectral characteristics of the interleaver in a 50 GHz channel spacing application exhibit a 0.5 dB passband larger than 43.8 GHz (88% of the spacing), a 25 dB stopband greater than 40 GHz (80% of the spacing), and a channel isolation higher than 35 dB. The result shows that the interleaver interferometer with novel GTE technique can simultaneously produce a 0.5 dB passband and a 25 dB stopband wider than other interferometer techniques.
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Liu, Baozhu. "Full-duplex 60 GHz band dense wavelength division multiplexing star tree architecture for radio-over-fiber systems." Thesis, 2004. http://spectrum.library.concordia.ca/8396/1/MR04383.pdf.
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In this work, full-duplex 60GHz DWDM star tree architecture for radio-over-fiber systems is investigated. New approach by using DWDM with the channel spacing of 25 GHz for the first time is proposed to improve the spectral efficiency. The demonstration system consists of 1 central station and 3 base stations as an example. In addition, the remote light source technique is utilized to simplify the architecture of base station (BS) and the external modulation technique is adopted to overcome the fiber chromatic dispersion. Especially, the MZ modulator, configured to generate optical single sideband (OSSB) signal, is adopted in the central station and modulates the optical carrier with the lower sideband (LSB) and upper sideband (USB) subcarriers simultaneously with different data and the EA modulator is adopted in the base station for implementing the maintenance-free BS in the future. The error-free transmission via the 25 km uplink and downlink fiber with the data rate of 155.52 Mbps is performed. The impact of the laser linewidth and the bandwidth of the electrical bandpass filter are investigated. It concludes that the system performance is limited by the laser phase noise for considered DPSK signal and the bandwidth of electrical bandpass filter is much larger than the 3-dB bandwidth. The trade-off has to be made when optimizing the laser linewidth and the bandwidth of the bandpass filter.