Page 170 - CITS - Electronic Mechanic - TT - 2024

ELECTRONICS MECHANIC - CITS

On the basis of Refractive Index:
Step-index optical fiber:
The refractive index of core is constant. The refractive index of the cladding is also constant. The rays of light
propagate through it in the form of meridional rays which cross the fiber axis during every reflection at the core-
cladding boundary

Graded index optical fiber:
In this type of fiber, the core has a non-uniform refractive index that gradually decreases from the centre towards
the core-cladding interface. The cladding has a uniform refractive index. The light rays propagate through it in the
form of skew rays or helical rays. it is not cross the fiber axis at any time.

On the basis of Material Used:
Plastic Optical Fibres: For transmission of light, polymethylmethacrylate is used as core material

Glass Fibres: It is an extremely fine glass fibres, core and cladding of the optical fibre is made of plastic.
Advantages of Fiber Optic Transmission:
Optical fibers have largely replaced copper wire communications in core networks in the developed world,
because of its advantages over electrical transmission. Here are the main advantages of fiber optic transmission
1 Extremely High Bandwidth:
No other cable-based data transmission medium offers the bandwidth that fiber does. The volume of data that
fiber optic cables transmit per unit time is far great than copper cables.
2 Longer Distance:
In fiber optic transmission, optical cables are capable of providing low power loss, which enables signals can be
transmitted to a longer distance than copper cables.
3 ResistancetoElectromagneticInterference:
In practical cabled eployment,it’s in evitable to meet environments like power substations, heating, ventilating and
other industrial sources ofinterference. However, fiber has a very low rate of bit error (10 EXP-13), as a result of
fiber being so resistant to electromagnetic interference. Fiber optic transmission is virtually noise free.

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CITS : E & H - Electronics Mechanic - Lesson 94 - 99