1. HANOI UNIVERSITY OF SCIENCE AND TECHNOLOGY
CENTER FOR TRAINING OF EXCELLENT STUDENTS
ADVANCED TRAINING PROGRAM
Hanoi 4-2013
Class: Materials Science Engineering
Teacher : NguyễnTuyết Nga
Student: HoàngVănTiến

2. contents
- Introduction
- General structures and properties
- Case study : fiber optics
- Introduction
- Optical Fiber & Communications System
- Modes and materials
- Optical fibers processing
- Applications
- Applications
- Conclusions and References

3. Introduction

4. Optical ceramics
 Materials with special light reflecting,
transmitting or other optical properties
include a wide range of glass compositions,
glass ceramics, and selected ceramics.
 Classification:
 Transparent ceramics : glass, optical fibers,
opticalswitches, laser amplifiers and lenses…
 Glass coloring
 Luminessence ceramics…

5. OPTICAL PROPERTIES OF CERAMICS
-REFRACTION
Light that is transmitted from one
medium into another, undergoes
refraction.
Refractive index, (n) of a material is
the ratio of the speed of light in a
vacuum (c = 3 x 108 m/s) to the speed
of light in that material.
n = c/v
5

6. OPTICAL PROPERTIES OF CERAMICS
6
Snell principal:

7. OPTICAL PROPERTIES OF CERAMICS
Callister, W., D., (2007), Materials Science And Engineering, 7th Edition,
7
30.04.2013

8. OPTICAL PROPERTIES OF CERAMICS
ABSORPTION
•Color in ceramics
Most dielectric ceramics and
glasses are colorless.
By adding transition metals
(TM)
Ti, V, Cr, Mn, Fe, Co, Ni
Carter, C., B., Norton, M., G., Ceramic Materials Science And Engineering,
8

9. Case study: fiber optics
(optical fibers )

10. Introduction
 An optical fiber is essentially a
waveguide for light
 It consists of a core and
cladding that surrounds the
core
 The index of refraction of the
cladding is less than that of
the core, causing rays of light
leaving the core to be
refracted back into the core
 A light-emitting diode (LED)
or laser diode (LD) can be
used for the source

11. Optical Fiber &
Communications System

12. Optical Fibers
 It has little mechanical strength, so it must be
enclosed in a protective jacket
 Often, two or more fibers are enclosed in the same
cable for increased bandwidth and redundancy in case
one of the fibers breaks
 It is also easier to build a full-duplex system using two
fibers, one for transmission in each direction
- Fiber optics ( optical fibers) is a flexible, transparent
fiber made of glass (silica) or plastic, slightly thicker
than a human hair. It functions as a waveguide, or
“light pipe”,to transmit light between the two ends
of the fiber

13. Types of Fiber
 Both types of fiber described earlier are known as step-index fibers because
the index of refraction changes radically between the core and the cladding
 Graded-index fiber is a compromise multimode fiber, but the index of
refraction gradually decreases away from the center of the core
 Graded-index fiber has less dispersion than a multimode step-index fiber

14. Why are fiber-optic systems revolutionizing
telecommunications?
Compared to conventional metal wire
(copper wire), optical fibers are……….

15. Less cost
Several miles of optical cable can be made
cheaper than equivalent lengths of copper
wire. This saves your provider (cable TV,
Internet) and you money.

16. Smaller-Thinner
Optical fibers can be drawn to smaller
diameters than copper wire.

17. Higher carrying capacity
Because optical fibers are thinner than copper
wires, more fibers can be bundled into a given-
diameter cable than copper wires. This allows
more phone lines to go over the same cable or
more channels to come through the cable to your
tv.

18. Less Signal Degradation
- The loss of signal in optical fiber is less
than in copper wire, so there is far less
“bleeding” on the lines.

19. Light signals
Unlike electrical signals in copper wires, light
signals from one fiber do not interfere with those
of other fibers in the same cable. This means
clearer phone conversations or TV reception.

20. Low power Requirement
Because signals in optical fibers degrade less,
lower-power transmitters can be used instead of
the high-voltage electrical transmitters needed
for copper wires. Again, this saves your provider
and you money.

21. Digital signals
Optical fibers are ideally suited for carrying
digital information, which is especially useful in
computer networks.

22. Non-flammable
Because no electricity is passed through
optical fibers, there is no fire hazard.

23. Lightweight
An optical cable weighs less than a comparable
copper wire cable. Fiber-optic cables take up less
space in the ground.

25. how do we make an optical
fiber?
 Materials : glass (silica) or plastic
 Making optical fibers requires the
following steps:
 Making a preform glass cylinder
 Drawing the fibers from the
preform
 Testing the fibers

26. Making a preform glass cylinder
 Purifying silica
 Mine sand (raw silica)
 React with chlorine to produce SiCl4 and other metals
from the impurities in the sand (FeCl3, etc.)
 Heat this mixture (essentially distilling)
 Collect SiCl4 vapors only
 Condense the pure SiCl4 vapors

27. modified chemical vapor
deposition (MCVD).
 Prepare a silica tube (glass extrusion).
 Heat the tube
 Inject SiCl4 and O2 into the tube
 At the heated portion, the SiCl4 is oxidized
The lathe turns continuously to make an even
coating and consistent blank
 UItra pure SiO2 is deposited on the inner walls
of the tube
 Draw the tube through the furnace, continuously
coating the inner walls.
 SiO2 particles deposit and sinter along the
tube, leaving a hollow core [for now].
2224 2ClSiOOSiCl heat

28. modified chemical vapor
deposition (MCVD).

29.  This technique can be used to manufacture very long
fibres (50 km). It is used for both step-index and graded-
index fibres.
Plasma-Enhanced Modified Chemical Vapour
Deposition (PMCVD)

30. Fiber drawing and protecting
 Anneal the multiwalled tube to the glass softening temperature.
 The tube and inner coating collapse to a solid, multilayered rod.
 Fire the rod at an even higher temperature softening it further.
 Draw the fiber through a nozzle, thinning the fiber dramatically.
 Core diameters from <5 to 500 um are used.
 Polymer coatings must also be applied.
 Fibers are finally bundled.

31. Fiber drawing
- The tip of the preform is heated to
about 2000 oC in a furnace.
- As the glass softens, a thin strand
of softened glass falls by gravity
and cools down.
- As the fiber is drawn its diameter is
constantly monitored
- A plastic coating is then applied to
the fiber, before it touches any
components.
- The fiber is then wrapped around a
spool.

32. Continuous production
 Fibers are drawn at 30 to 60
feet per second.
 Multiple polymer coatings
may be applied
 Thermoplastic (buffer)
 Aramid (strength)
 PVC of fluoride co-polymer
 Spools of up to several
kilometers are wound.
2000 C

33. Fiber optic diameter
 Plastic fiber has a core diameter of up
to 900 micrometer.
 20-30 feet max length.
 Easy to work with.
 Cheap.
 Glass fibers have cores from 8 to 62.5
micrometer across.
 Connecting two fibers end-to-end is
the hardest par—requires a
microscope or an automatic
connection of some kind.

34. Fiber testing
 Fibers must generally pass the following tests
 Tensile strength greater than 100,000 lb/in2
 Dimensional tolerance
 Temperature dependence
 Optical properties

35. Importance of Fiber Purity
 This complicated procedure is necessary due to the incredible sensitivity of
optical fiber communications to impurities and flaws.
 Fiber optics only became a reality in 1970, when Corning figured out how to
make fiber optics with less than 99% loss/km.
 Light transmission through 1 km of fiber drops to 1% of the input intensity if
there are only:
 2 Co atoms per billion
 20 Fe atoms per billion
 50 Cu atoms per billion
 Transmission in modern fibers is still limited to:
 60 to 75 percent/km for light with a wavelength of 850 nm.
 Transmission losses <1% have been achieved over >3000 miles.

36. Repeating Stations
 Repeating stations are generally placed at regular distances
along a fiber network to detect and amplify the signals since loss
will occur over km, or hundreds of km, of fiber.
 When light drops to 95% of transmission, a repeating station
is required.
 Since the cost of the repeaters is high compared to fiber,
tremendous effort goes into making pure, flaw free optical
fibers.
 Repeating stations today are generally 100 km apart for major
fiber bundles (trans-oceanic, etc).
http://www.telebyteusa.com/foprimer/foch2.htm

37. disadvantages
 difficult to install and test optical fibers
 fiber is a less familiar technology and
requires skills
 Fibers can be damaged easily if bent too
much
 fiber interfaces cost more than electrical
interfaces

38. Future fiber optic manufacturing?
 Why bother purifying Si and the trouble of making pure
and flaw-free fiber optics when a spider does it naturally?
http://www.newscientist.com/article.ns?id=dn3522

39. APPLICATIONS
- Optical fiber communication :
telecommunication
and computer networking
- Fiber optic sensors ( remove
sensing )
- Other uses…

40. Optical fiber communication

42. Fiber optic sensing systems (optical
sensors )
Two types :
-Intrinsic sensor : the sensors are internal or embedded into the
fibers
-Extrinsic sensors : the transducer is external to the fiber

43. how the environmental signal is
detected
 Informations (in terms of
intensity, phase, frequency,
polarization, spectral content,
etc.) are printed into the light
beam and is carried through the
optical fiber to an optical and/or
electronic processor.
The environmental signal is
perceived by the fiber optic itself
( as the light modulator )
-intrinsic sensor can be classified
as a distributed sensor, since it
allows the measurement to take
place in any point along the optic
fiber.

44. Properties of Fiber Optic
Sensing
 - Highly sensitive (more than other technologies)
 - Configuration versatility - point and distributed configurations possible
 - Dielectric construction (can be used with high voltages, high temperatures,
and stressed environments)
 -Wide dynamic range
 - Multiplexing capabilities
 - Freedom from electromagnetic interface (fibers carry no current)
 - Chemically passive
 - Provide real-time feedback
 - Resistant to corrosion
 - Multi point measurement (intrinsic sensors) or specific location sensing
(extrinsic sensors)

45.  -Ability to measure a wide range of different properties (wide range
of applications)
 - High resistance to extreme environments due to their robustness
and immunity to both electromagnetic and radio frequency
interference (intrinsic sensors).
 -They do not conduct electricity which means that the
measurements are not easily affected by external causes (intrinsic
sensors).
 - Extremely small size
 - Remotely powered
 -Ability to measure direct physical strain.
 - Sensors can placed upon the optic fiber

46. Input and Output
 Input: Light beam that carries the information
 Output:
-Extrinsic:
 1. encoder plates/disks: linear and angular position
 2. Evanescence: temperature, strain
 3. reflection and transmission: pressure, flow, damage
 4. Laser Doppler velocimetry: flow measurement
 5. total internal reflection: liquid level, pressure
 6. absorption Band edge: temperature
 7. Gratings: Pressure,Acoustics, vibrations
 8. Photo elastics effects: pressure, acceleration, vibration, rotatory, position.
 9. Fluorescence: temperature, viscosity, chemical analysis.
 10. Pyrometers: temperature.
- Intrinsic:
 1. Microbends sensors: strain, pressure, vibration.
 2. blackbody sensors: temperature
 3. interferometryc sensors: rotation acceleration, acoustics, magnetic fileds,
electric fields, strain, temperature, pressure, current.

47. Uses of Fiber optic sensing
systems
 testing machinery
 monitoring conditions in bridges or wind
turbines.
 used for industrial automation,
 biomedical technologies for digital
diagnostic imagery, Endoscopy…
 military, space, and automotive applications.

48. Example: Uses of Fiber optic
sensing systems in Endoscopy

49. SUMMARY
 Optical Fiber Processing
 Initial tube
 CVD of core
 Sintering and annealing
 coating
 applications

50. references
 Callister, W., D., (2007), Materials Science And Engineering, 7th
Edition,
 http://www.laserfocusworld.com/articles/2011/01/medical-
applications-of-fiber-optics-optical-fiber-sees-growth-as-
medical-sensors.html
 http://en.wikipedia.org/wiki/Optical_fiber
 http://www.ofsoptics.com/fiber/
 http://www.madehow.com/Volume-1/Optical-Fiber.html#b
 [4] John Crisp, Barry Elliott, Introduction to Fiber Optics, 3rd
edition, Newnes, 2005
 http://www.fiberopticproducts.com/
 http://www.fiber-optics.info/
 ………………………..