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Made available in DSpace on 2016-03-15T19:37:40Z (GMT). No. of bitstreams: 1 Palmerston Donizzeti Taveira.pdf: 3709250 bytes, checksum: f7776004371e059d73f0d20c8d735c07 (MD5) Previous issue date: 2006-08-02 / The 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%.

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.

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.

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.

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.

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.

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.

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.

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%.