Theoretical and experimental investigations of dynamic automatic gain control in multi-channel EDFA cascades and its implication on WDM multi-access lightwave networks performance.
Item
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Title
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Theoretical and experimental investigations of dynamic automatic gain control in multi-channel EDFA cascades and its implication on WDM multi-access lightwave networks performance.
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Identifier
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AAI9807962
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identifier
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9807962
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Creator
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Luo, Gengxian.
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Contributor
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Adviser: Mohamed A. Ali
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Date
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1997
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Language
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English
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Publisher
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City University of New York.
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Subject
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Engineering, Electronics and Electrical
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Abstract
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This thesis presents a detailed experimental and threoretical analysis of gain dynamics of an all-optically stabilized multi-channel EDFA and the impact on WDM networks performances. Specifically, this thesis analyzes and examines the critical factors such as, lasing wavelength, amplifier operating point, gain recovery time, relaxation oscillation frequency of the feedback loop, cavity structure, cavity length and losses, signal(s) and laser power, lasing direction, switching speeds, and the number of channels dropped/added, that affect the transient power excursions in the surviving channel. We show that any degradation at the first EDFA has a cumulative effect at the output of all subsequent EDFA's in the chain. This has the important implication that the length of the chain is a function of the design parameters of the first EDFA in the chain.;The main objective of this work is to protect surviving channels against such impairments, by minimizing the impact of variations in the number of wavelength channels in operation, and of rapid changers in their signal power levels. The basic requirement is that the quality of service for any given channel passing through an optical amplifier shall not be adversely impacted by anything that happens to any of other channels passing through the same amplifier. This requirement applies both to amplifiers in WDM repeaters network elements, and to amplifiers included in other network elements. We will consider means of adjusting the flattened-gain amplifier's total output power to maintain constant per-channel output power with a minimally degraded SNR, regardless of the number of channels present. This will require that the amplifier's control system be aware of the number of channels present. This information could be passed on a telemetry channel or derived through measurement at the amplifier.;This thesis is divided into two overlapping phases, experimental and theoretical. First, we consider the applicability of laser automatic gain control (AGC) to control fast power transients in WDM optical networks and reports the first high resolution measurements of transients in such gain controlled EDFA's. Second, we will implement a dynamic simulation tool for modeling the behavior of single amplifier and amplifier chains, with and without stabilization. We will develop an approximate rate equation model for a homogeneously broadened 3-level multi-excited-modes laser system. The experimental results are then compared with those predicted using the dynamic simulation tool.
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Type
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dissertation
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Source
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PQT Legacy CUNY.xlsx
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degree
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Ph.D.
