Flashcards in Optical Fibres Deck (111)
What is the shape of an optical fiber ?
How many parts does it basically consist of ?
What are they ?
Core and Cladding
Where is the core ?
It is the inner cylindrical part
What is the core generally made up of ?
Glass or plastic
What is the cladding ?
It is a concentric cylinder, surrounding the core
Which material has a higher refractive index ?
Core has a higher refractive index
What is used to prepare a jacket for the cladding ?
A polyurethane jacket
Why is it protected with a polyurethane jacket ?
It safeguards the fiber from chemical reaction,
What physical principle are optical fibers built on ?
Total internal reflection
Why is total internal reflection a special case of reflection ?
The ENTIRE incident energy is reflected back. There is ZERO absorption of light energy
Would fiber optics communication be possible if there was a very minute loss ?
No, it would be impossible
What is a waveguide ?
A tubular structure, which guides energy in the form of waves
Which property of light is generally used for analyzing signal propogation in fibers ?
What is fractional index change ?
It is the ratio of the refractive index difference of the core and cladding to the refractive index of the core
Do all the light rays that enter the core at an angle less than the angle of acceptance travel in the core, theoretically ?
No. Maxwell's laws tells us that only light waves of certain number of modes are sustained
Which parameter determines the number of modes supported for propagation ?
V - number
What is refractive index profile ?
The curve which represents the variation of refractive index with respect to the radial distance from the fiber axis
What are the three categories optical fibers are classified into ?
Single mode fiber
Step index multi mode fiber
Graded index multi mode fiber
What is a mode ?
Modes are the possible solutions of Helmholtz equations, combined with Maxwell's equations and the boundary conditions
What does a mode tell us about a wave ?
How a wave is distributed throughout space
Can two waves have the same mode ?
Yes, but with different frequencies
What is the diameter of the core in single mode optical fiber ?
8-10 micro meter
Which is the most commonly used optical fiber in the world ?
Single Mode Optical Fiber
Where do Single mode Optical Fibers find application, particularly ?
Submarine cable system
What is splicing ?
Joining the strands of one optical fiber to another
Can it be done with twisting and soldering ?
How is it done ?
The ends of respective strands are fused using mechanical splices
What is the special property of the core of Graded-Index Multimode Fiber ?
The refractive index decreases radially outward