PPT - Optical Fiber - Civil Engineering (CE) PDF Download

 Page 1


OPTICAL FIBER
1
Page 2


OPTICAL FIBER
1
Basic principle Total Internal Reflection in Fiber
An optical fiber (or fibre) is a glass or plastic fiber 
that carries light along its length.
Light is kept in the "core" of the optical fiber by total 
internal reflection. 
Page 3


OPTICAL FIBER
1
Basic principle Total Internal Reflection in Fiber
An optical fiber (or fibre) is a glass or plastic fiber 
that carries light along its length.
Light is kept in the "core" of the optical fiber by total 
internal reflection. 
3
What Makes The Light Stay in Fiber
?
Refraction
?
The light waves spread out along its beam.
?
Speed of light depend on the material used called 
refractive index.
?
Speed of light in the material = speed of light in the free 
space/refractive index
?
Lower refractive index ? higher speed
Page 4


OPTICAL FIBER
1
Basic principle Total Internal Reflection in Fiber
An optical fiber (or fibre) is a glass or plastic fiber 
that carries light along its length.
Light is kept in the "core" of the optical fiber by total 
internal reflection. 
3
What Makes The Light Stay in Fiber
?
Refraction
?
The light waves spread out along its beam.
?
Speed of light depend on the material used called 
refractive index.
?
Speed of light in the material = speed of light in the free 
space/refractive index
?
Lower refractive index ? higher speed
4
The Light is Refracted
This end travels 
further than the 
other hand
Lower Refractive index Region
Higher Refractive index Region
Page 5


OPTICAL FIBER
1
Basic principle Total Internal Reflection in Fiber
An optical fiber (or fibre) is a glass or plastic fiber 
that carries light along its length.
Light is kept in the "core" of the optical fiber by total 
internal reflection. 
3
What Makes The Light Stay in Fiber
?
Refraction
?
The light waves spread out along its beam.
?
Speed of light depend on the material used called 
refractive index.
?
Speed of light in the material = speed of light in the free 
space/refractive index
?
Lower refractive index ? higher speed
4
The Light is Refracted
This end travels 
further than the 
other hand
Lower Refractive index Region
Higher Refractive index Region
5
Refraction
?
When a light ray encounters a boundary separating two 
different media, part of the ray is reflected back into the first 
medium and the remainder is bent (or refracted) as it enters 
the second material. (Light entering an optical fiber bends in 
towards the center of the fiber – refraction)
Refraction
LED or 
LASER 
Source