The document discusses the history of optical transmission and fiber optics. Some key events and developments include: - In the 17th-19th centuries, early experiments explored using light for communication. - In the 1960s, theories for glass fiber optics were developed and the laser was invented, enabling long-distance fiber transmission. - Throughout the 1970s-1980s, fiber optic systems were tested and installed commercially as attenuation was reduced to less than 20 dB/km. - The 1990s saw widespread fiber optic cable installation globally and increased production capacities of hundreds of thousands of kilometers per year.

1. Introduction Siemens
Introduction
Contents
1 Definition of Fiber 3
2 History of Optical Transmission 7
3 Loss of a Few Optical Media 11
4 Advantages and Disadvantages of Optical Fibers 13
5 Principle of Transmission with Light 15
6 Regenerator Spacing 19
7 Exercise 21
8 Solution 25
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2. Siemens Introduction
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3. Introduction Siemens
1 Definition of Fiber
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4. Siemens Introduction
In optical transmission an effect of total internal reflection is desired. This effect
occurs if two transparent media are arranged one above the other. The external
medium must be "better" than the internal one.
The combination of glass and air would also fulfil this condition. However, one
achieves more favorable characteristics with two almost equally "good" types of
glass.
A technically functional optical fiber (OF) consists of the following components:
The information-carrying glass (the core) is covered
with a slightly "better" glass (the cladding).
A protective layer of plastic (the coating) is applied over the cladding.
This combination of core - cladding - coating is the fiber.
The fiber-glass factory delivers the fibers with a naturally colored coating.
If fibers are processed into cables, they are colored for identification in the cable
factory according to the specifications of the customer.
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5. Introduction Siemens
Fibre cross section
and
refraction index.
125
250
Potical fibres use din transmission applications have the following dimensions:
Diameter of the core approx.:8mm, 50 mm, 62,5 mm
Diameter with cladding:125 mm
Diameter with the coating:250 mm
Fig. 1
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6. Siemens Introduction
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7. Introduction Siemens
2 History of Optical Transmission
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8. Siemens Introduction
Use of light signals in the early epoch (such as signal fluch)
1626 Snell's law
1794 First telegraph line in France
1870 John Tydall demonstrated the light conductivity of a water jet
1880 Graham Bell developed the Opthophon (voice signals were sent via light but
were effected by the whether)
1888 Demonstration of electromagnetic waves by Hertz
1897 Analysis of the waveguide
1934 Norman R. French patented an optical telephone system using glass rods
or something similar in order to transport voice signals.
1958 Arthur Schawlow and Charles H. Townes developed the laser.
1960 Theodor H. Maiman operated the laser the first time.
1962 First semiconductor laser by GE, IBM, MIT
1966 Charles H. Kao and George A. Hockham proposed the glass fiber as
conductor.
1968 Optical wave guides with an attenuation of 1000 dB/km.
1970 Corning Glassworks produces an OWG with less than 20 dB/km at 633 nm.
1972 Attenuation of 4 dB/km at 850 nm and a bandwidth of 20 - 50 MHz/km is
achieved.
1973 The first FO cables for telephone purposes are employed on military
vessels.
1974 The concept for graded index fiber is introduced 500-1000 MHz/km.
1976 First system trials in the USA by Western Electric in Atlanta. Siemens starts
a 2.1 km long test line in Munich.
1977 Field trial in Chicago over 2.5 km by Bell Systems.
Simultaneously in Long Beach over 9.5 km by General Telephone.
Siemens installs the first FO link for DBP in Berlin.
1981 Dispersion 4 ps/nm x km Beales GB
1983 Siecor delivers the first single mode fiber cable.
1984 In the laboratory, over 200 km spans are achieved at 1.55 µm.
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9. Introduction Siemens
1985 Dispersion-shifted fiber
1987 Foundation of the Siecor company in Neustadt with 80,000 km processed
glass fiber. LA 140 LWL
1992 Siemens, together with Siecor, installs more than 3,000,000 km of cabled
fiber in over 25 countries. SLA 4/SLA 16
1995 The cable factory Neustadt processes 500,000 km fiber into cables for the
first time.
1996 Foundation of PT Trafindo Perkasa in Indonesia. The production starts
temporarily with 70,000 km of fiber.
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10. Siemens Introduction
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11. Introduction Siemens
3 Loss of a Few Optical Media
Medium Optical Attenuation Penetration depth at 50% light gloss
Pure Water 100,000 33 mm
Window glass 50,000 66 mm
Optical glass 3,000 1,000 mm
Thick fog 500 6,6 m
City air in Dusseldorf 10 330 m
Glass fibre 1970 20 165 m
Good fibre 1978 3 1,000 m
Good fibre 1986 0,2 18,000 m
Fig. 2
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12. Siemens Introduction
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13. Introduction Siemens
4 Advantages and Disadvantages of Optical
Fibers
Advantages:
l High transmission capacity
l Low susceptibility to electromagnetic interference important for use in industrial
plants control lines in power plants in principle, no spacing requirements when run
in parallel.
l Potential separation between transmitter and receiver (no ground loop)
l Long distances between repeaters over 300 km is possible for sea cables large
production lengths therefore greater distances between couplings therefore fewer
couplings therefore fewer installation errors.
l No line interference, no signal dispersion
l Highly resistant to eavesdropping
l Short-circuit-free (no spark formation) important in areas where there is a risk of
explosions.
l Light weight, highly flexible lighter equipment easier handling less volume for
shipping smaller cable reels lighter trailers smaller winches.
l Smaller dimensions smaller cable diameter more effective utilization of cable
ducts.
l No corrosion of fibers.
l Unlimited material availability (SiO2 is available in nearly limitless supply) 1 gram
of silicon corresponds to 10 kg of copper.#
Disadvantages:
l Installation technology
l high level of precision required
l sophisticated devices necessary
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14. Siemens Introduction
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15. Introduction Siemens
5 Principle of Transmission with Light
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16. Siemens Introduction
Message transmission with light can be easily explained:
In the transmitter, the electrical signal is converted into a light signal in an electro-
optical converter (e.g. a light emitting diode (LED) or a laser diode (LD)). To be more
precise: The light intensity of the transmitting diode is modulated by the binary pulse-
modulated diode current i1, and light with the power P (0) is coupled with the optical
fiber. After traversing the optical fiber, the light is converted back into an electrical
signal in an opto-electric converter (e.g. photodiode) at the end of the transmission
route. The optical transmission route therefore begins and ends with an electrical
interface whose data is normed independently of the transmission medium. There-
fore, digital systems with fiber optics use, in principle, the same interfaces (CCITT
recommendations G. 703) they use for radio relay and multiplex units.
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17. Introduction Siemens
CCITT Interface
Light-emitting optical
i1
or laser code transmitter
P (0)
Optical fibre
P (L)
Photodiode + i2 optical
- receiver
L Length of optical transmission route
i1, i2 Laser diode or photodiode current
P(0), P(L) Optical transmit or receive power
Fig. 3
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18. Siemens Introduction
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19. Introduction Siemens
6 Regenerator Spacing
The diagram shows regenerator spacing independently of transmission capacity and
the various transmission media.
An analog system (for example with 10,800 channels over a 2.6/9.5 coaxial cable)
requires a repeater every 1.55 km.
A glass fiber can transmit more than three times as many channels across approx.
100 km without a regenerator.
Maximum regenerator spacing
100
1500 nm
m
SM fibre
50
MM fibre
20
V300
V960
10
LA 34 KX
V2700
5
V3600
LA 140 KX coaxial pair 2.6/9.5 mm
2
LA 565 KX
V10800
1
100 200 500 1000 2000 5000 10000 20000 50000
565 Mbit/s
8 Mbit/s 34 Mbit/s 140 Mbit/s 622 2.5 Gbit/s
bit rate
Fig. 4
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20. Siemens Introduction
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21. Introduction Siemens
7 Exercise
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22. Siemens Introduction
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23. Introduction Siemens
Exercise
1. Name at least 5 decisive advantages of fiber-optic technology over standard
copper cable technology.
a)
b)
c)
d)
e)
2. In what year did the Corning Glassworks company succeed in manufacturing an
optical fiber with an attenuation of less than 20 dB/km (the beginning of fiber-
optic technology)?
3. Describe the basic design of a fiber-optic transmission route!
4. Name the three elements of an optical fiber.
a)
b)
c)
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24. Siemens Introduction
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25. Introduction Siemens
8 Solution
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26. Siemens Introduction
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27. Introduction Siemens
Solution
1. a) high transmission capacity
b) low weight
c) large production lengths
d) not susceptible to electromagnetic influence
f) resistant to eavesdropping
2. 1970
3. telephone - electro-optical converter - fiber - electro-optical converter - telephone
4. a) core
b) cladding
c) coating
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28. Siemens Introduction
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