1 OPTOELECTRONIC COMMUNICATIONS EKT 442. 2 MEETING LECTURE : 3 HOURS LABORATORY : 2 HOURS LECTURER Assoc. Prof. Dr. Syed Alwee Aljunid 017-5872667 [email protected]

1

OPTOELECTRONIC COMMUNICATIONS

EKT 442

2

MEETING • LECTURE : 3 HOURS• LABORATORY : 2 HOURS

LECTURERAssoc. Prof. Dr. Syed Alwee [email protected]

3

TextbookTextbook

• John Wilson and John Hawkes “Optoelectronics: An Introduction, 3nd Ed.” Prentice Hall, 1998.

4

ReferencesReferences• Joseph C. Palais “Fiber Optic

Communications, 5th Ed.” Prentice Hall, 2005.

• Ghatak and Thyagarajan“ An introduction to Fiber Optics”, Cambridge University Press, 1998.

• John. M. Senoir “Optical Fiber Communication: Principle and Practise, 2nd Ed. ”, Prentice Hall, 1993.

5

AssessmentAssessment

• Final Exam = 50 %

• Coursework = 50 %– Assignments/Quiz = 10 %– Tests = 10 % – Labs/Tutorials = 30 %

6

Syllabus:Syllabus:1. Light Properties2. Fundamentals of Fiber Optic3. Optical Components/Devices4. Light Sources5. Light Detectors, Noise and Detection 6. Optical Amplifiers7. System Design

7

Chapter 1.0 Chapter 1.0

Light Properties

8

ContentsContents

a)Electromagnetic radiationb)Frequency and wavelength of lightc) Refraction of lightd)Polarization of light

9

Electromagnetic radiationElectromagnetic radiation

10

analogphone

AMradio

mobilephone

microwave oven

X-rays

Wavelength

Frequency [Hz]102 103 104 105 106 107 108 109 1010 1011 1012 1013 1014 1015 1016 1017 1018

3000km 30km 300m 3m 3cm 0.3mm 3 mm 30nm 0.3nm

NFrange

HFrange

Microwavesrange

Opticalrange

X / gammarange

TV & FMradio

Wavelength range of electromagnetic transmission

Wavelength range of electromagnetic transmission

11

Frequency Hz

1800 1600 1400 1200 1000 800 600 400 200

2x1014 3x1014

5x1014

1x1015

Infraredrange

Ultravioletrange

wavelength nm

Visible range

1. Optical window 850 nm



Laserrange

Radarrange

Wavelength range of optical transmission

Wavelength range of optical transmission

12


Gamma rays, • highest-frequency electromagnetic energy • emitted by certain radioactive materials and also originate in outer space. • tremendous penetrating ability and able to pass through three meters of concrete!

13


X-rays • frequency just above ultraviolet • powerful enough to pass easily through many materials including soft tissues of animals. • This has led to the extensive use of X-rays in medicine to investigate textures in the human body.

14


Ultraviolet radiation • frequencies just above those of visible light • these rays have enough energy to kill living cells and cause tremendous tissue damage. • sun is a constant source of ultraviolet radiation • small doses of this light can promote the production of vitamin D and tan the skin. • Too much ultraviolet radiation can lead to serious sunburn. • Ultraviolet light is used extensively in scientific instruments to probe various systems, and it is also important in astronomical observations of the solar system, galaxy, and other parts of the universe.

15


Infrared radiation • This type of radiation is associated with the thermal region where visible light is not necessarily present. • For example, the human body does not emit visible light but it does emit infrared radiation which is felt as heat. • Almost all objects emit infrared rays, depending on the temperature of the object. Warmer objects emit more infrared radiation than cooler objects. • Common uses for infrared radiation are night vision scopes, electronic detectors, sensors in satellites and airplanes, and in astronomy

16


Microwave • The energy spectrum of microwaves has been utilized in oven technology

where the wavelength is tuned to frequencies that are readily absorbed by water molecules in food causing them to absorb energy and release heat as they vibrate.

• Microwaves are the highest frequency radio waves and are emitted by the Earth, buildings, cars, planes, and other large objects.

• Short wavelength microwaves are the basis for RADAR, which stands for radio detecting and ranging, a technique used in locating large objects and calculating their speed and distance.

17


Radio • well known for their ability to transmit radio and television signals. • wide spectrum of electromagnetic radiation• Radio waves used in communication usually consist of two types of transmissions:

amplitude modulated (AM) waves that vary in the amplitude of the wavelengths and frequency modulated (FM) waves that vary in wavelength frequency. FM radio waves are shorter in length than AM waves and tend to be blocked by large objects such as houses, buildings, and tunnels. AM waves are longer than FM waves and can be bent around these large objects to improve reception.

18


Visible light • comprises only a tiny portion of the entire electromagnetic

spectrum of radiation. • The wavelengths that we are able to see lie between 400 and 700

nanometers in length.

19


Visible Light Wavelength and Perceived Color

Wavelength Range(nanometers)

Perceived Color

340-400 Near Ultraviolet (UV; Invisible)

400-430 Violet

430-500 Blue

500-560 Green

560-620 Yellow to Orange

620-700 Orange to Red

Over 700 Near Infrared (IR; Invisible)

20

Frequency and wavelength of light


electrons moving in orbits around the nucleus of an atom are arranged in different energy levels within their electron clouds.

21



These electrons can absorb additional energy from outside sources of electromagnetic radiation, which results in their promotion to a higher energy level or electron cloud.

22



higher energies are associated with shorter wavelengths and lower energies are associated with higher wavelengths

23

Water tank

Light source

Expected way of the light

Effective way of the light

Total reflection at the boundary water-air

Light propagationLight propagation

24

Speed of light in vacuum: C0 = 299’793 km/sec.

Speed of light in glass: Cglass = 200’000 km/sec.

Milan Zurich

1 Millisecond

Milan Zurich1,5 Millisecond

Glas

Vacuum

Speed of lightSpeed of light

25

Wavelength (nm)

covered distance of a wave during one period (oscillation)

Frequency (Hz)

Number of oscillations (period per second)

Wavelength

Frequencyf

t

1 Sek.

Wavelength / FrequencyWavelength / Frequency

26


Frequency and wavelength of lightRelationship between wavelength and

frequency of light

c/

c is the speed of light is the frequency of the light in hertz (Hz)

is the wavelength of the light in meters

wavelength of light in inversely proportional to the frequency

Where:

27



relationship between the energy of a photon and it's frequency

E = h

E is the energy in kiloJoules per mole h is Planck's constant with a value of 6.626 x10-34 Joule-seconds per particle

E = hc/

energy of a photon is directly proportional to its frequency and inversely proportional to its wavelength

Where:

28



• Very high-frequency electromagnetic radiation such a gamma rays, x-rays, and ultraviolet light possess very short wavelengths and a great deal of energy.

• On the other hand, lower frequency radiation such as visible, infrared, microwave, and radio waves have correspondingly greater wavelengths with lower frequencies and energy.

Conclusion Conclusion

29

Nature of lightNature of light

30


31


32


33


34

ReflectionReflection

Total reflection

Perpendicularto division line

Division line Light path

Perpendicularto division line

Division lineLight path

Light reflection

35

Total reflection

Border ray

Light refraction

Light source

Optical denser Medium (n1)

Optical thinnerMedium (n2)

Light propagation in glass fiberLight propagation in glass fiber

36

Reflection of lightReflection of light

37

Refraction of lightRefraction of lightRefraction (or bending of the light) occurs as light passes from a one medium to another when there is a difference in the index of refraction between the two materials, and is responsible for a variety of familiar phenomena such as the apparent distortion of objects partially submerged in water.

When light passes from a less dense medium (such as air) to a more dense medium (such as water), the speed of the wave decreases.

38

Refraction of lightRefraction of lightRefractive index is defined as the relative speed at which light moves through a material with respect to its speed in a vacuum. By convention, the refractive index of a vacuum is defined as having a value of 1.0. The index of refraction, N (or n), of other transparent materials is defined through the equation:

Material Refractive Index

Air 1.0003

Water 1.33

Glycerin 1.47

Immersion Oil 1.515

Glass 1.52

Flint 1.66

Zircon 1.92

Diamond 2.42

Lead Sulfide 3.91

39

Refraction of lightRefraction of lightWhen light passes through a medium of high refractive index into a medium of lower refractive index, the incident angle of the light waves becomes an important factor.

If the incident angle increases past a specific value (dependent upon the refractive index of the two media), it will reach a point where the angle is so large that no light is refracted into the medium of lower refractive index,

40

Refraction of lightRefraction of lightThis phenomenon takes place when the angle of refraction (angle r in Figure 4) becomes equal to 90 degrees and Snell's law reduces to:

When the critical angle is exceeded for a particular wave, it exhibits total reflection back into the medium.

41

Refraction of lightRefraction of lightAnother important feature of light refraction, is that the wavelength of light has an impact on the amount of refraction in the same material. The amount of refraction is inversely proportional to the wavelength..

Thus, shorter wavelength visible light is refracted at a greater angle than longer wavelength light. White light is composed of all the colors in the visible spectrum. When this light is passed through a glass prism, the white light is dispersed into its component colors in a manner that is dependent upon the individual wavelengths

42

Polarization of lightPolarization of light

43

Diffraction of lightDiffraction of light

44

Difraction of lightDifraction of light

45

Difraction of lightDifraction of light

46


47


48


49


50

Brewster’s(Critical) angleBrewster’s(Critical) angle

51

Thank YouThank You

Documents

1 OPTOELECTRONIC COMMUNICATIONS EKT 442. 2 MEETING LECTURE : 3 HOURS LABORATORY : 2 HOURS LECTURER Assoc. Prof. Dr. Syed Alwee Aljunid 017-5872667 [email protected]