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Optical Communications

Optical Modulators: EAM and MZM

Optical modulators use electrical signals to modify the physical characteristics of materials in such a way that the propagation conditions of light change. This article explains the most common optical modulators that are widely employed in optical communications. Firstly, Electro-Absorption Modulators are briefly describred. Secondly, electro-optic Mach-Zehnder Modulators (MZM) are introduced. Finally, the most relevant […]

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Books

International Edition: List of Technical Books

Academic books in science and engineering tend to be expensive, both for students and professionals. When it comes to buying a copy of some of the most famous books in the field, prices are much higher than those of a conventional book. This phenomenon is especially relevant in emerging countries, where book prices in local […]

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Optical Communications

Laser Diodes for Optical Communications

The term laser is used as a noun, but it was originally an acronym for “light amplification by stimulated emission of radiation”. A laser is a fundamental part in any optical transmitter, as it is the generator of the optical carrier. In optical communications, the spectral location of a carrier is often stated in wavelengths […]

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Optical Communications

Optical Networks

This section provides a basic classification of optical networks. The overall network is a complicated system that ensures robust optical communications between exchange information nodes. This high-level system can be divided into typical subnetworks that meet specific geographical and functional requirements: the core network, Metropolitan Area Networks (MAN), access networks and Local Area Networks (LAN). […]

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Optical Communications

Relevance of Optical Communications

This article shows the relevance of optical communications emphasizing how the introduction of optical devices marked an inflexion point in the performance of guided data links. The development of electro-optical technology allowed to increase simultaneously the distance and capactiy of communications systems. In practice, optical communications have enabled the ever-increasing worldwide data traffic. The table […]

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Optical Communications

Optical Communications Fundamentals

Communication is an essential element in our social, cultural and technical evolution. Especially over recent decades, human habits and technology have influenced each other, but always relying on a growing exchange of information. Optical communications have enabled this development and have become the only mature technology that can satisfy the demand of capacity in wired […]

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Signals and Systems

Complex Envelope Implementation

The complex envelope is a baseband analytic signal. It is obtained by suppressing the negative (or positive) frequencies of a real bandpass signal, and transferring the remaining spectral content to baseband. Due to the complex notation and the spectral efficiency of the resulting signal, the complex envelope is very useful in both linear system simulation […]

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Signals and Systems

Analytic Signal and Complex Envelope

The analytic signal is a complex representation of a real signal, obtained by suppressing the negative frequency components of the original signal. From the analytic signal is derived the equivalent baseband signal, also an analytic representation known as complex envelope. Both representations are used in signal processing techniques due to their main advantages: spectral efficiency […]

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Signals and Systems

The Mathematics of Linear Distortion

The mathematics of linear distortion only applies to linear and time invariant systems [1] [2]. Therefore, these systems and their translation to the frequency domain, where the mathematical analysis is simplified, are briefly summarized. Then it is discussed how the presented theory can be applied to real transmission media and/or electronic components. Finally, the mathematics […]

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Programming

Create GIF Files in Octave and Matlab

Nowadays, in any technical work of a certain level, it is common to program and simulate codes in mathematical simulators such as Matlab, or its free “equivalent” Octave. Typically the results of these simulations can be part of documents, presentations and meetings. On many occasions we could benefit from motion graphics to better visualize, explain […]