Chapter 13: Optical Fiber Transmission Media - Review Notes

Reviewer and summary notes of the important concepts and formulas in Chapter 13 of the book "Introduction to Electronics Communications" by Wayne Tomasi.

Chapter 13: Optical Fiber Transmission Media

This is the summary notes of the important terms and concepts in Chapter 13 of the book "Electronic Communications System" by Wayne Tomasi. The notes are properly synchronized and concise for much better understanding of the book. Make sure to familiarize this review notes to increase the chance of passing the ECE Board Exam.

CHAPTER 13

OPTICAL FIBER TRANSMISSION MEDIA

Items

Definitions

Terms

1

Uses light as a carrier of information.

Optical communications

System

2

Electronic communications system is directly proportional to bandwidth.

Information-carrying

capacity

3

Bandwidth of an analog communications system as a percentage of its carrier frequency.

bandwidth utilization ratio

4

Device constructed from mirrors and selenium detectors that transmitted sound waves over a beam of light.

Photophone

5

Experimented with an apparatus called photophone.

Alexander Graham Bell

6

Used extensively in medical field.

Flexible fiberscope

7

Invented in 1960.

Laser (light amplification by stimulated emission of radiation)

8

Advantages of Optical Fiber cables.

1. wider bandwidth and greater information Capacity

2.immunity to crosstalk

3. immunity to statistic Interference

4. environmental

Immunity

5. safety and convenience

6. lower transmission loss

7. security

8. durability and reliability

9. economics

9

Disadvantages of Optical Fiber cables.

1. interfacing cost

2. strength

3. remote electrical Power

4. optical fiber cables are more susceptible to losses introduced by bending the cable

5. specialized tools, equipment, and training

10

Reduces the possibility of the occurrence of a detrimental phenomenon.

Stress corrosion

11

One wire is at the ground potential, whereas the other is at signal potential.

Single-ended or unbalanced

12

Protective coating.

Buffer jacket

13

Increases the tensile strength of the overall cable assembly.

Strength member

14

Process of decaying from one energy level to another energy level.

Spontaneous decay or spontaneous emission

15

Science of measuring only light waves that are visible to human eye.

Photometry

16

Measures the rate at which electromagnetic waves transfer light energy.

Optical power

17

Spectral separation of white light.

Prismatic refraction

18

Simply the ratio of velocity of propagation of a light ray in free space to the velocity of propagation of a light ray in a given material.

Refractive index

19

Angle at which the propagating ray strikes the interface with respect to the normal.

Angle of incidence

20

Angle formed between the propagating ray and the normal after the ray has entered the second medium.

Angle of refraction

21

Closely related to acceptance angle and is the figure of merit commonly used to measure the magnitude of the acceptance angle.

Numerical aperture

22

Simply means path.

Mode

23

More than one path.

Multimode

24

Probably the most important characteristic of the cable.

Power loss

25

Three factors that contribute to the absorption losses in optical fibers:

1. ultra violet absorption

2. infrared absorption

3. ion resonance absorption

26

Caused mainly by small bends and kinks in the fiber.

Radiation losses

27

Caused by excessive pressure and tension and generally occur when fibers are bent during handling or installation.

Contants-radius bends

28

Caused by the difference in the propagation times of light rays that take different path down a fiber.

Modal dispersion

29

A p-n junction made from two different mixtures of the same types of atom.

Mojunction structure

30

Generally constructed of silicon-doped gallium-arsenide.

Epitaxially grown

31

Homojunction LED’s output approximately 500 µ at a wavelength of 900 nm.

Planar diffused

32

Advantages of heterojunction devices over homojunction devices;

1. increase in current density generates a more brilliant light spot.

2. smaller emitting area makes it easier to couple its emitted light into a fiber.

3. small effective area has a smaller capacitance, which allows the planar heterojunction LED to be used at a higher speed.

33

Depletion-layer photo diode and is probably the most common device used as a light detector in fiber optic communications system.

PIN diode

34

Characteristic of a light detector.

1. responsivity

2. dark currents

3. transit time

spectral response

5. light sensitivity

Complete List of Reviewers in Electronic Communications System per Chapter

Important List of Communications Engineering Materials


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