1. The document discusses optical fibers, including their construction, principle of total internal reflection, types based on material, mode of propagation and index profile, and configurations including singlemode step-index, multimode step-index, and multimode graded index fibers. 2. Optical fibers have advantages like high bandwidth, immunity to interference, safety, security and economics due to low loss, but also have disadvantages like higher initial installation cost and need for specialized repair tools. 3. Applications of optical fibers include telecommunications, local area networks, cable TV, sensors, endoscopy, and decoration. Optical fibers are used to transmit data in telecommunications systems and endoscopic surgery.

1. Shantilal Shah
Engineering College,
Bhavnagar
INSTRUMENTATION AND CONTROL
ENGINEERING
( SEMESTER 1 )
1
Sidsar Campus, P.O. Vartej, Bhavnagar-364060
Phone: 0278-2445509, 2445767
Fax: 0278-2445509
Website: http://www.ssgec.ac.in/

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OUR GROUP
Members :
1. Jitin J Pillai
2.Dodiya Siddhraj
3.Kaneriya Yash
4.Dodiya Parth
5.Tripathi Vishal

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INTRODUCTION
Optical Fibers are hair-thin,
transparent strands through
which light can be transmitted.
A group of many such optical
fibers constitute a Optical Fiber
Cable.

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CONSTRUCTION
The main parts of an optical fiber are :
Core – thin glass center of the fiber
where light travels.
Cladding – outer optical material
surrounding the core.
Buffer Coating – plastic coating that
protects
the fiber.
Other protective coatings.

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PRINCIPLE
TOTAL INTERNAL REFLECTION is the main principle behind the
working of an optical fiber.
For T.I.R., conditions are satisfied :
• Light is incident on the walls of the cable at an angle greater than
the critical angle.
• The optical-fiber core is clad (coated) by a lower density glass
layer.

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FIBER TYPES
1. Plastic core and Plastic cladding
2. Glass core with Plastic cladding PCS (Plastic-Clad
Silicon)
3. Glass core and Glass cladding SCS (Silica-clad
silicon)
4. Under research: Zinc-chloride (non-Silicate)
 1000 time as efficient as glass
ON THE BASIS OF MATERIAL :

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ON THE BASIS OF MODE OF PROPAGATION :
1. Singlemode Fiber :
 Only one path for the propagation of light.
 The core is made very small (about 7-10 µm).
2. Multimode Fiber :
 More than one paths for the propagation of light.
 Core is larger in diameter (about 20-100 µm).

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ON THE BASIS OF INDEX PROFILE
1. Step-Index Fiber :
 Refractive index of the core as well as the cladding
is uniform.
 Light rays propagate in the form of meridional rays,
i.e. they follow a zigzag path and, for every
reflection they will cross the fiber axis.
2. Graded Index Fiber (GRIN Fiber):
 Refractive index of the core is not uniform, while
that of the cladding is uniform.
 Light rays propagate in the form of skew rays, i.e.
they follow a helical path and will never cross the
fiber axis.

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FIBER CONFIGURATIONS
I. Singlemode Step-Index Fiber (SMSI Fiber)
Single-mode step-index Fiber
n1 core
n2 cladding
no air
Light
ray
Index of
refraction

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II. Multimode Step-Index Fiber
Multimode step-index Fiber
n2 cladding
n1 core
no air
Index of
refraction

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III. Multimode Graded Index Fiber
Variable
n
Index profile
Multimode graded-index Fiber
Index of
refraction

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ADVANTAGES OF OPTICAL FIBER
 Capacity: much wider bandwidth (10 GHz)
 Crosstalk immunity
 Immunity to static interference
 Lightning
 Electric fields
 Florescent light
 Higher environment immunity
 Weather, temperature, etc.
 Safety: Fiber is non-metallic.
 No explosion, no shock
 Lasts longer.
 Security: tapping is difficult
 Economics: Fewer repeaters
 Low transmission loss (dB/km)
 Fewer repeaters
 Less cable
Remember:
Fiber is non-conductive
Hence, change of magnetic
field has
No impact!

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DISADVANTAGES OF OPTICAL FIBER
 Higher initial cost in installation
 Interfacing cost
 Less strength
 Lower tensile strength
 Remote electric power
 More expensive to repair/maintain
 Tools: Specialized and sophisticated

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APPLICATIONS
In Telecommunications to
transfer data.
In Local Area Networks to
share internet connections.
In Cable TV and CCTV.
In Optical Fiber Sensors.
In Endoscopy to view
internal body organs.
In decoration.

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Input
Signal
Coder or
Converter
Light
Source
Source-to-Fiber
Interface
Fiber-to-light
Interface
Light
Detector
Amplifier/Shaper
Decoder
Output
Fiber-optic Cable
Receiver
OPTICAL FIBERS ARE USED IN
TELECOMMUNICATION
Transmitter

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OPTICAL FIBERS ARE USED IN ENDOSCOPIC
SURGERY

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THANK YOU