Fiber Optic Tutorials

This is a continuation from the previous tutorial - laser pumping and population inversion.   The decoders we consider (which can include simplified versions such as binary message passing decoders) rely on the knowledge of the channel. The communication channel, or an equivalent communication channel comprising the physical channel as well as various inner receiver and signal processing stages, can be characterized by its conditional probability \(P(z|y)\), that is, the probability of observing \(z\) at the receiver assuming a transmitted modulation symbol \(y\in\boldsymbol{\mathcal{M}}\). Note that we restrict ourselves to memoryless channels, which can be achieved in practice by sufficiently long...

This is a continuation from the previous tutorial - polarization maintaining fibers.   The atomic rate equations introduced in the two previous tutorials are of great value in analyzing laser pumping, population inversion, and gain saturation in laser systems. The primary objective of this tutorial is to illustrate this point by solving the atomic rate equations and examining these solutions for some simple but important atomic systems.   1. Steady-State Laser Pumping and Population Inversion One of the most common applications for rate equations is in analyzing laser pumping. In this section, therefore, we will develop and solve the rate equations to...

This is a continuation from the previous tutorial - nondispersive prisms.   The purpose of this tutorial is to provide a practical, technical introduction to the field of polarization maintaining (PM) fiber that will equip the reader with the basic knowledge and understanding necessary to use or specify this category of specialty fiber. The tutorial begins by explaining how PM fibers work and provides brief examples of their various applications in sensing, medicine, and telecommunications, before describing the main fiber designs and the fabrication techniques used to produce them. The relatively new technology of ‘‘holey’’ or ‘‘microstructure’’ fibers is addressed briefly, as is one...

This is a continuation from the previous tutorial - half-shade devices and miniature polarization devices.   1. Glossary Here are the glossaries we are going to use in this tutorial. \(\delta\) - angular deviation \(\phi\) - phase \(\omega\) - radian frequency of rotation subscripts: A, B, C, D, d - prism dimensions \(t\) - time \(x\), \(y\) - rectangular components \(\alpha\) - angle 1, 2 - prism number   2. Introduction Prisms of various shapes and sizes are used for folding, inverting, reverting, displacing, and deviating a beam of light, whether it be collimated, converging, or diverging. Prisms, rather than...

This is a continuation from the previous tutorial - advances in detection and error correction for coherent optical communications - regular, irregular, and spatially coupled LDPC code designs.   Half-Shade Devices It is sometimes necessary to measure accurately the azimuth of a beam of plane-polarized light, i.e., the angle the plane of vibration makes with a reference coordinate system. This can be done most easily by using a polarizer as an analyzer and rotating it to the position where the field appears the darkest. The analyzer azimuth is then exactly \(90^\circ\) from the azimuth of the plane-polarized beam. A more...