Transcript No Slide Title

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ADAPT is a Human Resources Community Initiative supported by the European Union through the European Social Fund (ESF)
Overview
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ADAPT is a Human Resources Community Initiative supported by the European Union through the European Social Fund (ESF)
Wavelength and Spectra
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ADAPT is a Human Resources Community Initiative supported by the European Union through the European Social Fund (ESF)
Advantages of Fibre
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ADAPT is a Human Resources Community Initiative supported by the European Union through the European Social Fund (ESF)
Disadvantages of Fibre
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ADAPT is a Human Resources Community Initiative supported by the European Union through the European Social Fund (ESF)
Application Areas
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ADAPT is a Human Resources Community Initiative supported by the European Union through the European Social Fund (ESF)
Applications for Fibre in Buildings
Horizontal Cabling
Building Backbone
Most fibre is used in
campus and building
backbones
Horizontal cabling is
mainly copper at
present but may
become fibre
Campus Backbone
ADAPT is a Human Resources Community Initiative supported by the European Union through the European Social Fund (ESF)
Physical Cabling Structures
Physically cabling is always much more
complex than a simple point-to-point link
Cabling is installed in a variety of ways or
topologies
Typical example is a building backbone
Each fibre link on its own is a simple pointto-point link
But from a network perspective the system
may be configured as a ring or star network
Patch panels allow the collection of fibre links
to be configured in different ways
Building backbone
cabling
ADAPT is a Human Resources Community Initiative supported by the European Union through the European Social Fund (ESF)
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ADAPT is a Human Resources Community Initiative supported by the European Union through the European Social Fund (ESF)
Optical Fibre Construction
Cladding
Basic Fibre
Core
Fibre consists of a core surrounded by a cladding.
Most common material is silica glass
The core has a refractive index greater than that of the cladding
Core diameters range from 7 microns to 1 mm
ADAPT is a Human Resources Community Initiative supported by the European Union through the European Social Fund (ESF)
Propagation in a fibre
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ADAPT is a Human Resources Community Initiative supported by the European Union through the European Social Fund (ESF)
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ADAPT is a Human Resources Community Initiative supported by the European Union through the European Social Fund (ESF)
Decibels and Attenuation
Basic decibel power equation relates two absolute powers P1 and P2:
Power ratio in dB = 10 Log10[P1/P2]
In a fibre or other component with an input power Pin and an output power
Pout the loss is given by:
Loss in dB = 10 Log10 [Pout/Pin]
By convention the attenuation in a fibre or other optical component is
specified as a positive figure, so that the above formula becomes:
Attenuation in dB = -10 Log10[Pout/Pin]
ADAPT is a Human Resources Community Initiative supported by the European Union through the European Social Fund (ESF)
Absolute power in Decibels
It is very useful to be able to specify in dB an absolute power in watts or
mW.
To do this the power P2 in the dB formula is fixed at some agreed reference
value, so the dB value always relates to this reference power level.
Allows for the easy calculation of power at any point in a system
Where the reference power is 1 mW the power in an optical signal with a power level P
is given in dBm as:
Power in dBm = 10 Log [P/1mW]
10
Where the reference power is 1 W the power in an optical signal with a power
level P is given in dB as:
Power in dB = 10 Log [P/1W]
10
ADAPT is a Human Resources Community Initiative supported by the European Union through the European Social Fund (ESF)
Watts to dBm Conversion Table
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ADAPT is a Human Resources Community Initiative supported by the European Union through the European Social Fund (ESF)
Types of Attenuation
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ADAPT is a Human Resources Community Initiative supported by the European Union through the European Social Fund (ESF)
Transmission Windows
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ADAPT is a Human Resources Community Initiative supported by the European Union through the European Social Fund (ESF)
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ADAPT is a Human Resources Community Initiative supported by the European Union through the European Social Fund (ESF)
Types of Optical Fibre
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ADAPT is a Human Resources Community Initiative supported by the European Union through the European Social Fund (ESF)
Dispersion in an Optical Fibre
Fibre type influences so-called "Dispersion"
The higher the dispersion the lower the fibre bandwidth
Lower fibre bandwidths mean less information capacity
Modal Dispersion:
Reduced by using graded index fibre
Eliminated by using singlemode fibre
Material Dispersion:
Reduced by using Laser rather than LED sources
Reduced by operating close to 1320 nm
ADAPT is a Human Resources Community Initiative supported by the European Union through the European Social Fund (ESF)
Propagation in different Fibre Types
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ADAPT is a Human Resources Community Initiative supported by the European Union through the European Social Fund (ESF)
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ADAPT is a Human Resources Community Initiative supported by the European Union through the European Social Fund (ESF)