Fiber Optic Reference Guide: A Practical Guide to Communications Technology, Third Edition
This guide is an ideal primer for newcomers to the fiber optics industry as well as a useful reference guide for seasoned fiber optics veterans.
TABLE OF CONTENTS Fiber Optic Reference Guide: A Practical Guide to Communications Technology, Third Edition
Chapter 2: Fiber Optic Fundamentals
THE NATURE OF LIGHT
In order to understand some of the more complex components used in modern, high-performance, fiber optic transmission systems, one should have a good understanding of the nature of light. Many of light's properties are not obvious in our everyday lives, yet these properties are vital to the success of many modern fiber optic components. An important characteristic of light is the fact that light acts like a wave. (It can also act like a particle, but that is not pertinent to this discussion.) Light travels as an oscillating wave of electric and magnetic fields. As a result, two phenomena affect the behavior of light: interference and polarization, both important fundamentals in understanding and designing modern fiber optic components.
Interference
Interference forms the basis of many modern fiber optic components, including fiber Bragg gratings, optical filters built directly into the fiber; lithium niobate modulators, used to modulate the laser or LED externally rather than by internal circuitry; and many types of bulk filters, devices used in wavelength-division multiplexing.
In Figure 2.1, the top two curves represent two light waves traveling along the same path. The figure illustrates only the electrical fields. The distance between the crests or troughs of the waves is the light's wavelength. This is analogous to color or frequency in later discussions. The two light waves shown are also "in phase." This means the peaks and the valleys of the two waveforms are perfectly aligned. When two light waves have the same wavelength and...
Copyright Force, Incorporated 2002 under license agreement with Books24x7
