Chapter Overview

Optical communication systems use light to transmit information from one place to another. Light is a type of electromagnetic radiation like radio waves. Today, infrared light is being used increasingly as the carrier for information in a communication system. The transmission medium is either free space or a special light-carrying cable called a fiber-optic cable. Because the frequency of light is extremely high, it can accommodate very high rates of data transmission with excellent reliability. This chapter introduces the basic concepts, circuits and the most widely used optical networking technologies.

Chapter Outline

19-1 Optical Principles
19-2 Optical Communication Systems
19-3 Fiber-Optic Cables
19-4 Optical Transmitters and Receivers
19-5 Wavelength-Division Multiplexing
19-6 Passive Optical Networks

Chapter Objectives

• Define the terms optical and light. Name the three main bands of the optical spectrum, and state their wavelength ranges.
• State eight benefits of fiber-optic cables over electrical cables for communication. Name six typical communication applications for fiber-optic cable.
• Explain how light is propagated through a fiber-optic cable. Name the three basic types of fiber-optic cables, and state the two materials from which they are made. Calculate the transmission loss in decibels of fiber-optic cable and connectors over a distance.
• Name the two types of optical transmitter components and their main operating characteristics.
• Explain the operation of an optical detector and receiver.
• State the nature and frequency range of the infrared band, and name natural and artificial sources of infrared light.