Unit 2

Lesson 4 - Fiber Optic Cable

   Introduction

A fiber optic cable is a thin strand of glass or plastic, coated with a protective plastic jacket. It is so thin that even the glass fibers bend easily. A beam of light can be trapped within a fiber, so that the optical cable essentially becomes a pipe that carries light around corners.

Fiber optic networks can support high data rates, theoretically as high as 50 Gbps. An optical fiber can carry a light signal for a long distance (typically up to 2 kilometers [km]) before the signal must be strengthened. Because light is not appreciably affected by electromagnetic fields, optical signals are immune to EMI/RFI. This makes fiber a good choice for "noisy" environments with many electrical motors, such as elevator shafts and factories. Because fiber does not corrode, it is well suited for high-humidity and underwater environments. Optical fiber is also a highly secure medium, because it is difficult to splice into a fiber optic cable without detection.

The primary disadvantage of fiber optic cable is its cost. Fiber optic cable and equipment are relatively expensive in terms of both materials cost and installation. However, industries that need the high capacity and secure features of fiber find it well worth the investment. For example, nearly all long-distance telecommunication lines are fiber optic.

This lesson describes some of the typical components of fiber optic systems and the characteristics of fiber optic transmission.

   Objectives

At the end of this lesson you will be able to:

1.

Describe the composition of an optical fiber cable

2.

Explain how light travels down an optical fiber

3.

Name the main components of a fiber optic transmission system

Key Point
Fiber optic cable is expensive and demanding to install; however, it offers many unique advantages.


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