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Fiber Optic Tutorials


Fundamentals of Laser Oscillation

This is a continuation from the previous tutorial - mid-IR and infrared fibers.   This tutorial brings us finally to the complete laser oscillator: atoms, plus pumping and population inversion, plus signals and amplification, plus mirrors to provide feedback and oscillation. In this tutorial we will develop formulas for some of the simpler aspects of laser operation, including the population inversion required to reach oscillation threshold; the pumping power density required to produce this inversion; the laser power output, and its dependence on output coupling and pumping power in simple cases; the difference between homogeneously and inhomogeneously broadened lasers; and the atomic-frequency pulling...

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Mid-IR and Infrared Fibers

This is a continuation from the previous tutorial - optical fibers and fiber optic communications.   1. Introduction Infrared (IR) optical fibers are fibers that transmit radiation from 2 to approximately 20 μm. The first IR fibers were fabricated in the mid-1960s from a rather special class of IR transparent glasses called chalcogenide glasses. It was well known that mixing chalcogen elements, for example, arsenic and sulfur, can form a dark red glass that is transparent well beyond 2 μm. In 1965, this arsenic trisulfide (As2S3) glass was first drawn into crude optical fiber by Kapany et al., but the...

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Optical Fibers and Fiber Optic Communications

This is a continuation from the previous tutorial - analytical modeling of the impact of fiber non-linear propagation on coherent systems and networks.   1.  Principles of Operation The optical fiber falls into a subset (albeit the most commercially significant subset) of structures known as dielectric optical waveguides. The optical fiber works on principles similar to other waveguides, with the important inclusion of a cylindrical axis of symmetry. For some specific applications, the fiber may deviate slightly from this symmetry; it is nevertheless fundamental to fiber design and fabrication.   Figure 1. (a) Generic optical fiber design, (b) path of a...

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Analytical Modeling of the Impact of Fiber Non-Linear Propagation on Coherent Systems and Networks

This is a continuation from the previous tutorial - laser mirrors and regenerative feedback.   1. Why Are Analytical Models Important? Analytical models of the impact of non-linear effects on system and network performance are important for several reasons: in the context of point-to-point (PTP) systems, they allow to explore design strategies efficiently, without resorting to lengthy computer simulations; in the context of networks, they can help in the optimization of the network architecture and layout, and can provide physical layer awareness for real-time control-plane tasks such as channel routing. In all contexts, they can be used for research purposes,...

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Laser Mirrors and Regenerative Feedback

This is a continuation from the previous tutorial - chiral fibers   1. Laser Mirrors and Beam Splitters Laser mirrors and beam splitters have certain fundamental properties that are important to understand. Before discussing the use of mirrors in laser cavities, let us therefore review the more important of these properties.   Single Dielectric Interface   Figure 11.1. Reflection and transmission of optical waves at a dielectric interface.   The simplest example of a partial mirror or beam splitter is the interface between two dielectric media, as shown in Figure 11.1. Suppose we write the normalized fields for the incident and...

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