Made available in DSpace on 2014-06-12T17:39:58Z (GMT). No. of bitstreams: 2 arquivo6992_1.pdf: 9302355 bytes, checksum: 8eed24999ba8c6de78c08f97a68ff38c (MD5) license.txt: 1748 bytes, checksum: 8a4605be74aa9ea9d79846c1fba20a33 (MD5) Previous issue date: 2004 / Nessa dissertação apresentamos um novo conceito para otimização de sistemas WDM solitônicos, chamado Gerenciamento de Colisões. Mostramos resultados de simulações com sistemas WDM solitônicos de amplificação discreta de 2 x 40 Gb/s, operando próximo do zero de dispersão, na banda C de transmissão, sem o uso de gerenciamento de dispersão ou quaisquer outras técnicas já consagradas (como por exemplo filtros ao longo do enlace) de minimização de efeitos físicos prejudiciais ao desempenho do sistema. Após fundamentar e explorar o conceito de Gerenciamento de Colisões, propomos o uso de três técnicas. A primeira trata-se do gerenciamento de colisões incompletas que podem ocorrer no início e no final da transmissão. Para viabilizar este gerenciamento propomos uma técnica que consiste na inserção de um atraso inicial entre pulsos de canais diferentes. Esta técnica, em um sistema otimizado, para condições apropriadas (comprimento de colisão maior que duas vezes o comprimento de amplificação), pode permitir uma melhora no desempenho de sistemas WDM solitônicos, chegando a dobrar o alcance dos mesmos, pois ela elimina a colisão incompleta inicial e, em determinados casos, a final. Outras duas técnicas sugeridas exemplificam que, por meio do gerenciamento das colisões completas, podemos melhorar o desempenho de sistemas WDM solitônicos, otimizando adequadamente o espaçamento entre canais, bem como, o espaçamento entre amplificadores do mesmo. Verificamos que a otimização correta de Sistemas WDM Solitônicos, aliado ao uso adequado do espaçamento entre canais e amplificadores, pode permitir ao sistema um alcance em torno de 1000 km, para uma taxa de erro por bit (BER) de aproximadamente 10-12, sem o uso da técnica de gerenciamento de colisão incompleta, e em torno 1600 km com a utilização da mesma

Long-haul optical fiber communication system is an important infrastructure to support the latest broadband communication in the world. It is important to study a technology to improve the performance of such system, and the Return-to-Zero Differential Phase Shift Keying (RZ-DPSK) modulation attracts much attention because of its improved long distance transmission performance. One important technology of the current long-haul optical fiber communication system is the dispersion map, and it is widely deployed for already installed undersea optical fiber communication system in the world. Recently, a new dispersion map that was totally different from the map used for already deployed system was proposed, and it demonstrated advantageous performance of the long-haul RZ-DPSK transmission. Even though, the reason of the performance improvement is not investigated, and it is important to clarify the physical mechanism of the performance improvement, because it will contribute to improve the system design of the long-haul optical fiber communication systems in near future. In this master thesis, the performance of the RZ-DPSK format in the long-haul transmission system is studied. Both computer simulations and experiments are conducted to confirm the effects of various factors in the long-haul RZ-DPSK transmission system. From the theoretical study, it is pointed out that the Self-Phase Modulation (SPM) played a significant role to degrade the transmission performance of the conventional map, while it does not cause so significant degradation in the new map. The effects of the SPM and the Cross-Phase Modulation (XPM) with the conventional map are investigated through the experimental study.

With the essence of robustness toward fiber nonlinearity owing to the increasingly required high-speed data rate from the country to country or country to the state, many useful methods are proposed upon the long-haul optical fiber transmission, such as modulation format, dispersion map and repeater spacing, etc. Return-to-zero differential phase shift keying (RZ-DPSK) format was chosen in this master thesis because of its high tolerance toward nonlinear effect in the wavelength-division multiplexing (WDM) system transmission. It has been realized that the system performance is wavelength-dependent by the combination of the WDM technology and the RZ-DPSK system with the commonly used block-type dispersion map, especially for the significant performance difference between including or excluding the self-phase-modulation (SPM) effect. Therefore, it is quite significant to investigate the unwanted fiber nonlinearity. In this master thesis, the influence relating to the cross-phase modulation (XPM) effect and the SPM effect with the conventional dispersion map after long distance transmission is the mainly concerned issue to be discussed. In this master thesis, both experiment and theoretical simulation are investigated. On the theoretical simulation part, the Q-factor of the system zero dispersion wavelength at 1543.8nm, 1550nm, 1556.2nm were degraded and their value were less than 10dB. The Q-factor was around 1.5dB less than the averaged value. However, the performance of the long-haul RZ-DPSK system based on the block-type dispersion map shows no significant performance by shifting the system zero dispersion wavelength out of the WDM signal wavelength band. On the experimental part, the impact of the XPM effect and the SPM effect on the long-haul optical fiber communication system is investigated quantitatively. For the XPM experiment, the system performance was just only 0.1 dB difference after 6000km transmission. On the contrary, for the SPM experiment, the Q-factor between best and worst performance was up to 1.3dB difference. At last, the experiment and the simulation support each other successfully in this master thesis.

The aim of this thesis was introducing the options of conversion between OTDM and WDM technologies. Since this issue is rather extensive, first of all the principle of optical transmission system is described. One chapter presents the effects influencing the optical transmissions. Material absorption, linear and nonlinear scattering and bending losses are mentioned in terms of fiber losses, followed by description of waveguide, chromatic and polarization-mode dispersion of optical fibers. Last part of the chapter presents nonlinear effects, including self-phase modulation, cross-phase modulation and four-wave mixing. The practical part of the thesis deals with multichannel systems. The principles of frequency, space a hybrid multiplexing are explained. Multichannel systems with optical time domain multiplexing and waveguide multiplexing are described in detail and compared. The elements of the transmission chain of multiplex, such as different types of lasers, detectors, modulators, optical amplifiers, splitters, couplers, MUX and DEMUX are discussed. The next part of the thesis was aimed at suggesting the model of mutual conversion between OTDM and WDM systems. First of all, the previously performed experiments concerning the conversion between OTDM and WTM were evaluated. Then the model of OTDM/WDM/OTDM conversion was designed, with explanation of its parts and their function. The general recommendations for practical implementation were are also included. Due to the limited amount of time reserved for access to the simulation program Optsim, the simulations were performed only for certain parts of the proposed conversion model. At the end of the thesis, the proposed model is evaluated.

This thesis explores the theoretical foundations of cross-phase modulation (XPM) between optical fields in the N-configuration atom. This is the process by which the refractive index experienced by one field can be modulated by controlling the intensity of another. The electro-optical version of this effect was first discovered by John Kerr in 1875 and found applications in photonics as a means of very rapidly modulating the phase and intensity of electromagnetic fields. Due to recent advances in experimental techniques there has been growing interest in generating nonlinear optical interactions in coherently prepared atomic ensembles. The use of coherently prepared media brings the possibility of achieving a much larger cross-phase modulation than is possible using classical materials. This is particularly useful when trying to create large optical nonlinearities between low-intensity electromagnetic fields. Much of the current research into cross-phase modulation is directed towards realising potential applications in the emerging field of quantum information processing. Above all, the possibility of constructing an all-optical quantum computer has been at the heart of much research and controversy in the field. In this thesis the theory of steady-state, transient and pulsed cross-phase modulation is developed. Moreover, care has been taken to relate all research back to experimentally feasible situations. As such, the relevance of the theory is justified by consideration of the situation present in rubidium-87. Due to the close relationship between XPM in the N-configuration atom and electromagnetically induced transparency in the Lambda-atom, many similarities and insights act as link between these two fields. Indeed, it is frequently demonstrated that the key to understanding the various properties of XPM in the N-configuration atom is by comparison with the situation in the corresponding Lambda-atom equivalent.

Στην εργασία αυτή γίνεται προσομοίωση της Διασταυρούμενης Διαμόρφωσης Φάσης που λαμβάνει χώρα σε ένα SOI κυματοδηγό υπό την προϋπόθεση της μηδενικής διασποράς. Για να καταλήξουμε στο μοντέλο προσομοίωσης παρουσιάζονται τα μη-γραμμικά οπτικά φαινόμενα τα οποία συμμετέχουν στο υπό μελέτη φαινόμενο καθώς επίσης και τα χαρακτηριστικά του κυματοδηγού που επιδρούν στην διάδοση του παλμού. Το τελικό μοντέλο λαμβάνει επίσης υπόψη του τις βασικές ιδιότητες του πυριτίου και τις διεργασίες που γίνονται σ’ αυτό κατά την διάρκεια της αλληλεπίδρασης του υλικού με την οπτική ακτινοβολία. Τα αποτελέσματα που δίνει το μοντέλο είναι η επίδραση της έντασης του παλμού άντλησης στην μεταβολή της φάσης του διαδιδόμενου κύματος και κατά συνέπεια την μεταβολή του μήκους κύματος. / In this work becomes simulation of Cross-Phase Modulation (XPM) that takes place in a silicon-on-insulator (SOI) waveguide under the condition less-dispersion. In order to we lead to the model of simulation are presented the nonlinear optical phenomena which participate in under study phenomenon as well as the characteristics of waveguide that affect in the propagation of pulses. The final model takes into consideration the basic properties of silicon and the activities that become in this at the duration of interaction of material with the optical radiation. The results that it gives the model are the effect of intensity of pump pulse in the change of phase of propagated wave and accordingly the change of wavelength.

This thesis studies and mathematically models nonlinear interactions among channels of modern high bit rate (amplitude/) phase modulated optical systems. First, phase modulated analogue systems are studied and a differential receiving method is suggested with experimental validation. The main focus of the rest of the thesis is on digital advanced modulation format systems. Cross-talk due to fiber Kerr nonlinearity in two-format hybrid systems as well as 16-QAM systems is mathematically modelled and verified by simulation for different system parameters. A comparative study of differential receivers and coherent receivers is also given for hybrid systems. The model is based on mathematically proven assumptions and provides an intuitive analytical understanding of nonlinear cross-talk in such systems. / Graduate

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.

Four different trials of stratified three-layered fine paper, of sulphate pulp, were performed to investigate if stratified fine fraction or fibres from birch can improve the properties of a paper compared to a reference sheet. All trials had five different scenarios and each scenario was calendered with different linear load. All sheets had a grammage of 80 g/m2.In the first trial, the paper contained birch, pine and filler of calciumcarbonate (marble), and was manufactured with the pilot paper machine XPM and the stratified headbox Formator at RCF (Stora Enso Research Center in Falun). The furnish consisted of 75% birch and 25% pine.The second trial contained coated sheets with paper from trial one as the base paper. The coating slip contained calciumcarbonate and clay and the amount was approximately 10-12 g/m2.The third trial, also with birch and pine but without filler, was performed at STFI (Skogsindustrins Tekniska Forskningsinstitut in Stockholm) with the laboratory scaled paper machine StratEx and the stratified headbox AQ-vanes. The furnish consisted of 75% birch and 25% pine, except for one scenario which contained of 75% pine and 25% birch.The last trial contained fractionated pulp of birch and pine and was performed at STFI. 50% was fine fraction and 50% was coarse fraction.This test does not show any clear benefits of making stratified sheets of birch and pine when it comes to properties such as bending stiffness, tensile index and surface smoothness. The retention can be improved with birch in the surface plies. It is possible that the formation can be improved with birch in the surface plies and pine in the middle ply. It is also possible that fine fraction in the surface plies and coarse fraction in the middle ply can improve both surface smoothness and bending stiffness. The results in this test are shown with confidence intervals which points out the difficulties of analysing sheets manufactured with a pilot paper machine or a laboratory scaled paper machine.

FundaÃÃo de Amparo à Pesquisa do Estado do Cearà / Nesta dissertaÃÃo foi estudada a aplicaÃÃo do filtro AcÃstico-Ãptico SintonizÃvel (AOTF), com a ModulaÃÃo de Pulsos por PosiÃÃo (PPM), objetivando implementar, utilizando o mÃtodo de Runge-Kutta de 4a ordem, portas lÃgicas (OR-OU e AND-E) Ãpticas operando com pulsos de luz ultracurtos (2ps). Neste trabalho à investigado o desempenho das portas considerando vÃrios comprimentos do filtro ( L) que integra a sua estrutura interna, com o intuito de obter o comprimento de filtro mais adequado para uma operaÃÃo satisfatÃria, em regime dispersivo, nÃo linear, sem perdas e com modulaÃÃo de fase cruzada (XPM). Esta investigaÃÃo à realizada em duas situaÃÃes: primeiramente, sÃo considerados filtros com automodulaÃÃo de fase (SPM) e GVD (dispersÃo da velocidade de grupo). Em um segundo momento, as mesmas portas sÃo obtidas com efeitos SPM, XPM e GVD agindo juntos no AOTF. Foi observado que para pulsos do tipo sÃliton, os efeitos da dispersÃo, da nÃo linearidade e da modulaÃÃo de fase cruzada exercem juntos uma forte influÃncia na propagaÃÃo do mesmo, provocando a quebra do pulso na saÃda do dispositivo quando utilizamos um comprimento maior para os filtros. Para dispositivos mais curtos, o pulso chaveado apresentou compressÃes e alargamentos temporais e espectrais, bem comodeslocamentos temporais nos dois modo de propagaÃÃo (TE e TM). ApÃs a escolha de um comprimento de filtro adequado, foi selecionado um deslocamento temporal Ãtimo a ser aplicado nos pulsos de entrada para conseguirmos, na saÃda da porta lÃgica, deslocamentos temporais satisfatÃrios (acertos) na aplicaÃÃo da modulaÃÃo PPM. Em seguida, introduzimos fases em um dos pulsos de entrada (TM), provocando um defasamento entre os pulsos TE e TM, reduzindo ainda mais a margem de erro PPM de operaÃÃo das portas. Finalmente, ao analisarmos as fases aplicadas no pulso TM (0 a 2), definirmos o melhor Ãngulo de fase para que as portas operem na regiÃo de acerto da modulaÃÃo PPM. / In this dissertation it was studied the application of the Acoustic Optical Tunable Filter (AOTF), with Pulse Position Modulation (PPM), aiming at to implement, using the method of Runge-Kutta of 4a order, logical gates (OR and AND) optical operating with pulses of light ultra shorts (2ps). In this work the acting of the gates is investigated, considering several lengths of the filter (  L) that integrates your internal structure, with the intention of obtaining the length of more appropriate filter for a satisfactory operation, in dispersion regime, nonlinear, without losses and with Cross Phase Modulation (XPM). This investigation is accomplished in two situations: firstly, filters are considered with Self Phase Modulation (SPM) and GVD (group-velocity dispersion). In a second moment, the same gates are obtained with effects SPM, XPM and GVD, acting together in AOTF. It was observed that for pulses of the type soliton, the effects of the dispersion, of the nonlinearity and of the cross phase modulation exercise together a strong influences in the propagation of the same, provoking the break of the pulse in the exit of the device when we used a larger length for the filters. For shorter devices, the switched pulse presented temporary and spectral compression and spread, as well as, displacement in the time in the two propagation modes (TE and TM). After the choice of a length of appropriate filter, a great temporary displacement was selected to be applied in the input pulses for us to get, in the exit of the logical gate, satisfactory temporary displacements (successes) in the application of the PPM modulation. Soon after, we introduced phases in one of the entrance pulses (TM), provoking a phase displacement among TE and TM pulses, still reducing more the margin of error PPM of operation of the gates. Finally, to the we analyze the applied phases in the pulse TM (0 to 2), we defined the best phase angle for the gates to operate in the success area of the PPM modulation.