Fiber Optic Tutorials

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...

This is a continuation from the previous tutorial - the Rabi frequency.   1. Introduction Forward error correction (FEC) in optical communications has been first demonstrated in 1988. Since then, coding technology has evolved significantly. This pertains not only to the codes but also to encoder and decoder architectures. Modern high-speed optical communication systems require high-performance FEC engines that support throughputs of 100 Gbit/s or multiples thereof, that have low power consumption, that realize net coding gains (NCGs) close to the theoretical limits at a target bit error rate (BER) of less than \(10^{-15}\), and that are preferably adapted to...

This is a continuation from the previous tutorial - rare earth-doped fibers.   Both the linear susceptibility approach and the rate equation analysis we have developed in the past several tutorials are approximations—though usually very good approximations—to the exact dynamics of an atomic system with an external signal applied. If a very strong (or very fast) signal is applied to an atomic transition, however, the exact nonlinear behavior of the atomic response becomes more complicated, and the rate-equation approximation is no longer adequate to describe the atomic response. In this tutorial, therefore, we explore the conditions under which the rate-equation approximation...