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A Cost-Benefit Analysis on Modulation Formats for 40-Gb/s Optical Communication Systems

SILVEIRA, Clenilson Rodrigues da; PATACA, Daniel M.; ROMERO, Murilo A.; ROCHA, Monica de Lacerda
Fonte: TAYLOR & FRANCIS INC Publicador: TAYLOR & FRANCIS INC
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
57.657783%
This article discusses possible approaches for optical network capacity upgrade by considering the use of different modulation formats at 40 Gb/s. First, a performance evaluation is carried out regarding tolerance to three impairments: spectral narrowing due to filter cascading, chromatic dispersion, and self-phase modulation. Next, a cost-benefit analysis is conducted, considering the specific optoelectronic components required for the optical transmitter/receiver configuration of each format.; Fundacao de Apoio a Pesquisa do Estado de Sao Paulo (FAPESP)[06/045464-4]; Conselho Nacional de Desenvolvimento Cientifico e Tecnologico (CNPq); Fundo para o Desenvolvimento Tecnologico das Telecomunicacoes (FUNTTEL), Brazil

Efeito Kerr magneto-óptico espectral e sperimagnetismo de filmes amorfos de terra rara-Co; Spectral magneto-optical Kerr effect and magnetism-speri of the films of amorphous rare earth-Co

Tufaile, Adriana Pedrosa Biscaia
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Tese de Doutorado Formato: application/pdf
Publicado em 28/05/2001 PT
Relevância na Pesquisa
57.960566%
Observamos o comportamento espectral do efeito Kerr transversal, para filmes amorfos de terra rara - cobalto na região do espectro visível e ultravioleta próximo (comprimento de onda, , entre 325 nm e 670 nm), onde o sinal magnetoóptico apresentou um máximo na região azul do espectro. Concluímos que, para esta região espectral, a variação relativa de refletividade é proporcional à magnetização do cobalto e a constante de proporcionalidade depende da composição da liga e do comprimento de onda da luz. Desenvolvemos uma técnica de modulação de fase, própria para medir o efeito Kerr transversal e a comparamos com a técnica de modulação de amplitude. Montamos um magnetômetro a efeito Kerr que opera com a modulação de fase e utiliza um laser de He-Cd ( = 325 nm e 442 nm) ou um diodo laser vermelho ( = 670 nm). Fazendo uma analogia com a figura de mérito para os efeitos Kerr longitudinal e polar (Fe), nós propusemos uma figura de mérito para o efeito Kerr transversal (FJ. Mostramos que sua dependência do ângulo de incidência é semelhante à da variação relativa de refletividade e, comparando medidas da figura de mérito do efeito Kerr longitudinal com a figura de mérito para o efeito transversal, comprovamos que a grandeza proposta é um bom parâmetro para medida de qualidade magnetoóptica de materiais. Observamos os efeitos do sperimagnetismo de ligas com anisotropia local fraca (Gd-Co) e forte (Ho-Co)...

Geração de harmônicos de pulsos laser de femtossegundo pela técnica de conversão de frequência em capilares preenchidos com gases nobres; Harmonics generation of femtosecond laser pulses by the technique of frequency conversion in noble gas filled capillaries

Siqueira, Jonathas de Paula
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Tese de Doutorado Formato: application/pdf
Publicado em 26/06/2012 PT
Relevância na Pesquisa
68.482383%
O propósito principal desta tese foi a implementação e estudo da geração de pulsos laser de femtossegundos em comprimentos de onda curtos (ultravioleta profundo, ultravioleta de vácuo e ultravioleta extremo) pela técnica de conversão de frequência em capilar preenchido com gás nobre. Esta técnica de conversão de frequência tem feito diversas contribuições nas últimas décadas para o avanço da geração de pulsos laser ultracurtos nesta região espectral. O desenvolvimento de tais fontes de luz coerente possui importantes implicações nos estudos de espectroscopia resolvida no tempo em átomos, moléculas e materiais. Através da implementação da técnica de conversão de frequência com casamento de fase em capilar preenchido com gás argônio, foi possível a obtenção de pulsos de femtossegundos centrados em 260 nm e 195 nm utilizando um sistema laser amplificado Ti: safira (780 nm, 1.5 mJ, 43 fs, 1 KHz). Estes comprimentos de onda correspondem, respectivamente, aos terceiro e quarto harmônicos da frequência fundamental do laser utilizado. Pulsos centrados em 260 nm com excelente perfil espacial, energias da ordem de microjoules e durações temporais tão curtas quanto 18 fs, possibilitadas pela recompressão por um par de prismas...

Sistemas CDMA ópticos coerentes baseados em codificação de fase espectral; Coherent optical CDMA systems based on spectral phase coding

Bertarini, Pedro Luiz Lima
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Tese de Doutorado Formato: application/pdf
Publicado em 11/12/2012 PT
Relevância na Pesquisa
67.753755%
Este trabalho faz uma extensa e detalhada análise de sistemas ópticos coerentes baseados na tecnologia de acesso múltiplo por divisão de código, com ênfase naqueles em que o processo de codificação do sinal óptico é realizado por meio de deslocamentos de fase no domínio espectral (SPECTS-OCDMA). Apesar de ser um estudo numérico, esforços são concentrados na tentativa de aproximar estes cenários simulados aos cenários mais realistas, implementados em laboratórios. Nesse contexto, levando em consideração o impacto dos efeitos dispersivos e nãolineares da fibra óptica em sistemas SPECTS-OCDMA, são modelados diversos dispositivos que constituem o sistema de recepção do sinal óptico (nonlinear optical loop mirror e nonlinear thresholder), e mostradas suas influências no desempenho do sistema. Isso permite identificar o exato grau de interferência que cada código de uma determinada família de códigos causa nos outros códigos da mesma família. Esta análise é diferente de tudo previamente reportado para os sistemas OCDMA, porque até então sempre se supôs que todos os códigos de uma mesma família têm o mesmo desempenho. Também é demonstrado que uma escolha ótima do conjunto de códigos reduz consideravelmente a taxa de erro de bit (BER). Os conjuntos ótimos de códigos são obtidos em termos do padrão de interferência causado por todos os códigos no usuário de interesse. Isso permite mostrar que o uso de conjuntos ótimos de códigos não só melhora o desempenho geral do sistema em termos de BER...

Linear readout of dynamic phase modulation index in an optical voltage sensor using the new J(1) ... J(3) spectral method

Marcal, Luiz A. P.; Vendramini, Ericsson; Higuti, Ricardo T.; Kitano, Claudio; IEEE
Fonte: IEEE Publicador: IEEE
Tipo: Conferência ou Objeto de Conferência Formato: 219-223
ENG
Relevância na Pesquisa
57.525845%
The J(1)...J(3) is a recent optical method for linear readout of dynamic phase modulation index in homodyne interferometers. In this work, the J(1)... J(3) method is applied to measure voltage in an optical voltage sensor. Based on the classical J(1)...J(4) method, the J(1)... J(3) technique shows to be more stable to phase drift and simpler for implementation than the original one. The sensor dynamic range is enhanced. The agreement between theoretical and experimental results, based on 1/f noise, is demonstrated.

Caracterização espectral e avaliação de desempenho para formatos avançados de modulação digital optica em 40 Gb/s; Spectral characterization and performance evaluation for advanced digital optical modulation formats at 40 Gb/s

Francisco Augusto da Costa Garcia
Fonte: Biblioteca Digital da Unicamp Publicador: Biblioteca Digital da Unicamp
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 07/08/2009 PT
Relevância na Pesquisa
57.59787%
Comparamos o desempenho de quatro arquiteturas de recuperação de portadora tipo feedforward em receptores QPSK e 8-PSK coerentes com multiplexação de polarização e decodificação diferencial. Analisamos os cenários que apresentam desequilíbrio entre as SNRs nas duas polarizações, tal como ocorre em sistemas com PDL. Usando simulações de Monte Carlo, observamos que o método de estimação conjunta proposto apresenta penalidade em SNR de 1,1 dB de penalidade em SNR para uma razão largura de linha/ taxa de símbolo = 5 × 10-3, enquanto as outras três arquiteturas investigadas têm penalidade de 1,8 dB, 2,0 dB, e 3,9 dB para o formato de modulação QPSK. Para o formato 8-PSK, a arquitetura de recuperação conjunta apresenta 1,1 dB para uma razão largura de linha/ taxa de símbolo = 7, 5 × 10-4, enquanto as outras três arquiteturas têm penalidade 1,5 dB, 1,7 dB e 2,8 dB, para BER = 10-3 e um desequilíbrio em SNR de 3 dB; This work compares the performance of four feedforward carrier recovery architectures in coherent QPSK and 8-PSK receivers, with polarization multiplexing and differential decoding. We focused on the scenarios showing an SNR imbalance between orthogonal polarizations, as in PDL impaired systems. Using Monte Carlo simulations...

Advanced optical modulation and format conversion; Modulação e conversão de formatos óticos avançados

Dionísio, Rogério Pais
Fonte: Universidade de Aveiro Publicador: Universidade de Aveiro
Tipo: Tese de Doutorado
ENG
Relevância na Pesquisa
47.86118%
Over the years, the increased search and exchange of information lead to an increase of traffic intensity in todays optical communication networks. Coherent communications, using the amplitude and phase of the signal, reappears as one of the transmission techniques to increase the spectral efficiency and throughput of optical channels. In this context, this work present a study on format conversion of modulated signals using MZI-SOAs, based exclusively on all- optical techniques through wavelength conversion. This approach, when applied in interconnection nodes between optical networks with different bit rates and modulation formats, allow a better efficiency and scalability of the network. We start with an experimental characterization of the static and dynamic properties of the MZI-SOA. Then, we propose a semi-analytical model to describe the evolution of phase and amplitude at the output of the MZI-SOA. The model’s coefficients are obtained using a multi-objective genetic algorithm. We validate the model experimentally, by exploring the dependency of the optical signal with the operational parameters of the MZI-SOA. We also propose an all-optical technique for the conversion of amplitude modulation signals to a continuous phase modulation format. Finally...

Cross-phase modulation spectral shifting: nonlinear phase contrast in a pump-probe microscope

Wilson, Jesse W.; Samineni, Prathyush; Warren, Warren S.; Fischer, Martin C.
Fonte: Optical Society of America Publicador: Optical Society of America
Tipo: Artigo de Revista Científica
Publicado em 04/04/2012 EN
Relevância na Pesquisa
47.99041%
Microscopy with nonlinear phase contrast is achieved by a simple modification to a nonlinear pump-probe microscope. The technique measures cross-phase modulation by detecting a pump-induced spectral shift in the probe pulse. Images with nonlinear phase contrast are acquired both in transparent and absorptive media. In paraffin-embedded biopsy sections, cross-phase modulation complements the chemically-specific pump-probe images with structural context.

Plasma-induced self-phase and cross-phase modulation of femtosecond laser pulses

Le Blanc, Stephen Paul
Fonte: Universidade Rice Publicador: Universidade Rice
ENG
Relevância na Pesquisa
48.502246%
The spectral, temporal, and spatial characteristics of plasma-induced self-phase and cross-phase modulation in rare gases have been investigated using a femtosecond KrF excimer laser focused to peak intensities of 10$sp{14}$-10$sp{15}$ W cm$sp{-2}.$ The quiver energy of a free electron under these conditions is less than the ionization potential of all rare gases, ensuring that ionization occurs only by optical field-induced processes. Spectral blueshifts of up to 2 nm have been observed, and the blueshifted spectra show an oscillatory structure. The blueshifted spectra are shown to be the result of plasma-induced self-phase modulation and can be modeled by assuming tunneling ionization and one dimensional pulse propagation. The newly discovered oscillatory structure in the spectra is related to that observed in earlier experiments on self-phase modulation in optical fibers. To investigate the temporal behavior of the field ionization process, pump-probe experiments have been performed with a 100 fs probe pulse at 497 nm and a 400 fs pump pulse at 248 nm. Under conditions of weak ionization (Z $ll$ 1), pump-probe experiments and theoretical calculations show that the ionization rate of the field ionized gas is maximum at the peak of the laser pulse and that the degree of ionization changes over a time equal to about half of the pump pulse width. By observing changes in the transmission of the probe pulse caused by plasma absorption...

Code design and multiuser detection for code division multiple access systems with continuous phase modulation

Papasakellariou, Aristides
Fonte: Universidade Rice Publicador: Universidade Rice
ENG
Relevância na Pesquisa
47.74618%
The proliferation of wireless communications services combined with the limited spectrum availability have placed the bandwidth utilization as a major performance measure. Consequently, the bandwidth allocation technique to multiple signals and the bandwidth occupied by each signal are issues of paramount importance. For voice and bursty data communications, code-division multiple-access provides excellent bandwidth management. The objective to produce constant-envelope signals with compact spectral characteristics is most effectively accomplished using continuous phase modulation. The purpose of this study is to examine detection issues for signals that combine the above techniques. For a synchronous system, the reliable operation of a single-user receiver without power control requires spreading codes that exhibit minimal mutual interference. Signal memory is essential for good performance and precludes the existence of orthogonal codes. Code design is examined for two signal formats that offer different spectral and error rate characteristics. A recursive algorithm that provides the structure and maximum number of codes is presented for both signal formats. Moreover, the code performance is evaluated for an asynchronous system with power control. To avoid the performance limitations of the single-user receiver in the presence of interference and the disadvantages of power control...

Wavelength-Preserving Polarization-Insensitive All-Optical 3R Regenerator Based on Self- and Cross-Phase Modulation and Offset Filtering Utilizing Raman Amplification

CHUNG, SUNG HAN
Fonte: Quens University Publicador: Quens University
Tipo: Tese de Doutorado Formato: 3818044 bytes; application/pdf
EN; EN
Relevância na Pesquisa
47.98903%
Optical regeneration has the potential to significantly increase the reach of long-haul transmission systems. In this thesis, wavelength-preserving polarization-insensitive all-optical 3R regeneration is investigated and demonstrated for 10 and 40 Gb/s signals. The all-optical regenerator utilizes a self-pulsating laser for clock recovery, cross-phase modulation (XPM) based spectral broadening in a highly nonlinear fiber (HNLF) and offset filtering for retiming, and self-phase modulation based spectral broadening in a HNLF and offset filtering for reshaping. Raman amplification is used to increase the XPM-based spectral broadening and thus allow a design that meets the tradeoffs involved in simultaneously achieving good retiming and reshaping performance. The regenerator is shown to reduce amplitude noise and timing jitter while not causing a BER penalty. To fully validate the regeneration scheme, the cascadability is demonstrated using a recirculating loop. For a 10 Gb/s signal, with a regenerator spacing of 240 km, a return-to-zero, on-off-keyed (RZ-OOK) signal was transmitted over 18,000 km (75 loops) with a power penalty of 1.6 dB at a BER of 1E-9 compared to the back-to-back case. For a 40 Gb/s signal, with a regenerator spacing of 80 km...

Nuevos esquemas de conformación de pulsos láser ultracortos; Design of novel system for ultrashort laser pulse shaping

González Inchauspe, C.M.
Fonte: Facultad de Ciencias Exactas y Naturales. Universidad de Buenos Aires Publicador: Facultad de Ciencias Exactas y Naturales. Universidad de Buenos Aires
Tipo: info:eu-repo/semantics/doctoralThesis; tesis doctoral; info:eu-repo/semantics/publishedVersion Formato: application/pdf
Publicado em //1997 SPA
Relevância na Pesquisa
57.714526%
Se presentan en este trabajo nuevos sistemas para la expansión y recompresión temporal de pulsos ultracortos y la modulación de la fase espectral de los mismos. De las distintas posibilidades que estos ofrecen, nos hemos abocado particularmente a sus aplicaciones en la técnica de amplificación de pulsos con barrido en frecuencia (CPA). Se proponen sistemas para cada una de las etapas de la técnica de CPA: expansión, amplificación y recompresión de pulsos laser ultracortos.Con estos sistemas se han logrado resolver algunos de los problemas más críticos que aparecen en el proceso de amplificación de pulsos y que se traduce en pulsos mal conformados, ensanchados temporalmente y con colas que impiden su aplicación en ciertos experimentos. Se ha hecho un análisis completo de los sistemas, estudiando sus efectos sobre el pulso. Estos efectos incluyen tanto la parte temporal y espectral como la espacial. Se estudian las posibles aberraciones que estos sistemas puedan introducir y se determinan los parámetros y condiciones de funcionamiento.; We propose novel systems for the temporal stretching, compression and spectral phase modulation of ultrashort pulses. Among the differents posibilities that these systems offer, we have aimed our work to its' apllicattions in the technique of chirped pulse amplification (CPA). We have designed systems for each step in the CPA technique: stretching...

Black hole in a waveguide: Hawking radiation or self-phase modulation?

Smolyaninov, Igor I.
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
47.758%
Recently it was suggested that Hawking radiation may be observed in a nonlinear electromagnetic waveguide upon propagation of an optical pulse. We show that the spectral characteristics of the Hawking effect in such a waveguide are indistinguishable from the well-known effect of frequency broadening of an optical pulse due to self-phase modulation. Furthermore, we derive an estimate on the critical optical power at which Hawking effect is dominated by the self-phase modulation. It appears that optical experiments reported so far are clearly dominated by self-phase modulation.; Comment: 11 pages, 1 figure

On the effects of self- and cross-phase modulation on photon purity for four-wave mixing photon-pair sources

Bell, Bryn; McMillan, Alex; McCutcheon, Will; Rarity, John
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 14/04/2015
Relevância na Pesquisa
48.269546%
We consider the effect of self-phase modulation and cross-phase modulation on the joint spectral amplitude of photon pairs generated by spontaneous four-wave mixing. In particular, the purity of a heralded photon from a pair is considered, in the context of schemes that aim to maximise the purity and minimise correlation in the joint spectral amplitude using birefringent phase-matching and short pump pulses. We find that non-linear phase modulation effects will be detrimental, and will limit the quantum interference visibility that can be achieved at a given generation rate. An approximate expression for the joint spectral amplitude with phase modulation is found by considering the group velocity walk-off between each photon and the pump, but neglecting the group-velocity dispersion at each wavelength. The group-velocity dispersion can also be included with a numerical calculation, and it is shown that it only has a small effect on the purity for the realistic parameters considered.; Comment: 11 pages, 10 figures

Self-phase modulation of spherical gravitational waves

Mendonca, J. T.; Cardoso, V.; Marklund, M.; Servin, M.; Brodin, G.
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 08/07/2003
Relevância na Pesquisa
47.85824%
Self-phase modulation of spherical gravitational wavepackets propagating in a flat space-time in the presence of a tenuous distribution of matter is considered. Analogies with respect to similar effects in nonlinear optics are explored. Self phase modulation of waves emitted from a single source can eventually lead to an efficient energy dilution of the gravitational wave energy over an increasingly large spectral range. An explicit criterium for the occurrence of a significant spectral energy dilution is established.; Comment: 11 pages

Soliton Formation in Whispering-Gallery-Mode Resonators via Input Phase Modulation

Taheri, Hossein; Eftekhar, Ali A.; Wiesenfeld, Kurt; Adibi, Ali
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
47.758%
We propose a method for soliton formation in whispering-gallery-mode (WGM) resonators through input phase modulation. Our numerical simulations of a variant of the Lugiato-Lefever equation suggest that modulating the input phase at a frequency equal to the resonator free-spectral-range and at modest modulation depths provides a deterministic route towards soliton formation in WGM resonators without undergoing a chaotic phase. We show that the generated solitonic state is sustained when the modulation is turned off adiabatically. Our results support parametric seeding as a powerful means of control, besides input pump power and pump-resonance detuning, over frequency comb generation in WGM resonators. Our findings also help pave the path towards ultra-short pulse formation on a chip.; Comment: 4 pages, 4 figures

Self- and cross-phase modulation of ultrashort light pulses in an inertial Kerr medium: spectral control of squeezed light

Popescu, F.; Chirkin, A. S.
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
47.775527%
Quantum theory of self-phase and cross-phase modulation of ultrashort light pulses in the Kerr medium is developed with taking into account the response time of an electronic nonlinearity. The correspondent algebra of time-dependent Bose-operators is elaborated. It is established that the spectral region of the pulse, where the quadrature fluctuations level is lower than the shot-noise one, depends on the value of the nonlinear phase shift, the intensity of another pulse, and the relaxation time of the nonlinearity. It is shown that the frequency of the pulse spectrum at which the suppression of fluctuations is maximum can be controlled by adjusting the other pulse intensity.; Comment: LaTeXe, 19 pages, 7 figures, revised version, to appear in J. Opt. B: Quantum and Semiclass. Opt. (2002) http://www.iop.org/, style files included

Generation of Pulse Sequences with Periodic Spectral Phase Masks

Barmes, Itan; Ruehl, Axel
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 14/01/2014
Relevância na Pesquisa
57.50116%
We present a method for the generation of complex pulse sequences by using periodic spectral phase modulation. An analytical expression is derived for the temporal profile of such pulse sequences, which relates the temporal amplitudes and phases of the subpulses to the Fourier components of the periodic phase mask. We consider two families of periodic phase masks, namely, when a single period is an odd or even function, and discuss the differences between the resulting pulse sequences. The ability to generate pulse sequences with more degrees of freedom provides an alternative parametrization for investigating quantum coherent control landscapes. This is illustrated in the context of dark pulses in nonresonant two-photon absorption.; Comment: 5 pages and 3 figures. Comments are appreciated

Spectral phase conjugation with cross-phase modulation compensation

Tsang, Mankei; Psaltis, Demetri
Fonte: Optical Society of America Publicador: Optical Society of America
Tipo: Article; PeerReviewed Formato: application/pdf
Publicado em 17/05/2004
Relevância na Pesquisa
48.057964%
Spectral phase conjugation with short pump pulses in a third-order nonlinear material is analyzed in depth. It is shown that if signal amplification is considered, the conversion efficiency can be significantly higher than previously considered, while the spectral phase conjugation operation remains accurate. A novel method of compensating for cross-phase modulation, the main parasitic effect, is also proposed. The validity of our theory and the performance of the spectral phase conjugation scheme are studied numerically.

Dispersion and nonlinearity compensation by spectral phase conjugation

Tsang, Mankei; Psaltis, Demetri
Fonte: Instituto de Tecnologia da Califórnia Publicador: Instituto de Tecnologia da Califórnia
Tipo: Article; PeerReviewed Formato: application/pdf
Publicado em 01/09/2003
Relevância na Pesquisa
47.67327%
We propose the use of spectral phase conjugation to compensate for dispersion of all orders, self-phase modulation, and self-steepening of an optical pulse in a fiber. Although this method cannot compensate for loss and intrapulse Raman scattering, it is superior to the previously suggested midway temporal phase conjugation method if high-order dispersion is a main source of distortion. The reshaping performance of our proposed scheme and a combined temporal and spectral phase conjugation scheme in the presence of uncompensated effects is studied numerically.