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BY:Sagar Adroja
1.Linear Scattering Losses
Rayleigh Scattering losses
MIE Scattering losses

2.Absorption Losses

Ultraviolet Abosorption
...
Q. What is a

Light Scattering?

The propagation of light through the core of an
optical fiber is based on total internal
...
Linear Scattering
Light Scattering typically
characterized by wide variety of
reflection angles.
Light scattering depends on
the wavelength ...


The scattering of light in optical
quality glass fiber is caused by
molecular level irregularities
(compositional fluct...


Atoms and other particles inevitably scatter
some of the light that hits them. The light
isn't absorbed, just sent in a...
Rayleigh scattering of light.
However, the distinction between
scattering and absorption doesn't matter
much if you are trying to send light
through a f...
The closer the wavelength is to the particle size,
the more scattering. In fact, the amount of
scattering increases quite ...
Rayleigh scattering is more evident after sunset.
Rayleigh scattering causes the blue hue of the daytime sky and the reddening of the sun at sunset
Rayleigh scattering of sunlight in the
atmosphere causes diffuse sky
radiation, which is the reason for the blue
color of ...
v

If the size of the defet is greater than
one-tenth of the wavelength of
light,the scattering mechanism is
called MIE Sc...
The irregularities in the core,cladding interface,
Their refractive index difference along the fiber
Length,diameter fluct...
Removing imperefctions due to glass
manufacturing process.
Carefully controlled extrusion and coating of
the fiber.
Increa...
Absorption is a major cause of signal loss in an
optical fiber.
Absorption is defined as the portion of
attenuation result...
Imperfections in the atomic structure of the
fiber material
The intrinsic or basic fiber-material properties

The extrinsi...
Imperfections in the atomic structure induce
absorption by the presence of missing molecules
or oxygen defects.
Is also in...


Intrinsic absorption is caused by basic fibermaterial properties.
If an optical fiber were absolutely pure, with no
imp...
In fiber optics, silica (pure glass) fibers are used
predominately. Silica fibers are used because of
their low intrinsic ...


In silica glass, the wavelengths of operation
range from 700 nanometers (nm) to 1600 nm.
This wavelength of operation i...
Intrinsic absorption in the ultraviolet region is caused
by electronic absorption bands. Basically, absorption
occurs when...
Extrinsic absorption is caused by impurities
introduced into the fiber material.
Trace metal impurities, such as iron, nic...
Silica (pure glass) fibers are used because of
their low intrinsic material absorption at the
wavelengths of operation. Th...
Bending the fiber also causes attenuation.
Bending loss is classified according to the
bend radius of curvature: microbend...
Macrobend losses are observed when a fiber
bend's radius of curvature is large compared to
the fiber diameter.
Fiber sensi...
Losses in fiber
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Losses in fiber

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Losses in fiber

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Losses in fiber

  1. 1. BY:Sagar Adroja
  2. 2. 1.Linear Scattering Losses Rayleigh Scattering losses MIE Scattering losses 2.Absorption Losses Ultraviolet Abosorption Infared Absorption Ion Resonance Absorption
  3. 3. Q. What is a Light Scattering? The propagation of light through the core of an optical fiber is based on total internal reflection of the lightwave. Rough and irregular surfaces, even at the molecular level, can cause light rays to be reflected in random directions. This is called diffuse reflection or scattering, and it is typically characterized by wide variety of reflection angles.
  4. 4. Linear Scattering
  5. 5. Light Scattering typically characterized by wide variety of reflection angles. Light scattering depends on the wavelength of the light being scattered. Basically, scattering losses are caused by the interaction of light with density fluctuations within a fiber. Density changes are produced when optical fibers are manufactured.
  6. 6.  The scattering of light in optical quality glass fiber is caused by molecular level irregularities (compositional fluctuations) in the glass structure. There are tow types of scattering Losses. (1)Rayleigh scattering Losses. (2)MIE scattering Losses.
  7. 7.  Atoms and other particles inevitably scatter some of the light that hits them. The light isn't absorbed, just sent in another direction in a process called Rayleigh scattering, after the British physicist Lord Rayleigh, as shown in Figure.
  8. 8. Rayleigh scattering of light.
  9. 9. However, the distinction between scattering and absorption doesn't matter much if you are trying to send light through a fiber, because the light is lost from the fiber in either case. Scattering depends not on the specific type of material but on the size of the particles relative to the wavelength of light.
  10. 10. The closer the wavelength is to the particle size, the more scattering. In fact, the amount of scattering increases quite rapidly as the wavelength decreases. For a transparent solid, the scattering loss in decibels per kilometer is given by where A is a constant depending on the material.
  11. 11. Rayleigh scattering is more evident after sunset.
  12. 12. Rayleigh scattering causes the blue hue of the daytime sky and the reddening of the sun at sunset
  13. 13. Rayleigh scattering of sunlight in the atmosphere causes diffuse sky radiation, which is the reason for the blue color of the sky and the yellow tone of the sun itself. Scattering by particles similar to or larger than the wavelength of light is typically treated by the Mie theory or the discrete dipole approximation.
  14. 14. v If the size of the defet is greater than one-tenth of the wavelength of light,the scattering mechanism is called MIE Scattering. Mie scattering ,caused by these large defects in the fiber core,scatters light out of the fiber core.
  15. 15. The irregularities in the core,cladding interface, Their refractive index difference along the fiber Length,diameter fluctuation. There all are irregularities produced these mie scattering.
  16. 16. Removing imperefctions due to glass manufacturing process. Carefully controlled extrusion and coating of the fiber. Increase the fiber guidance ,which depends on refractive index difference.
  17. 17. Absorption is a major cause of signal loss in an optical fiber. Absorption is defined as the portion of attenuation resulting from the conversion of optical power into another energy form, such as heat.
  18. 18. Imperfections in the atomic structure of the fiber material The intrinsic or basic fiber-material properties The extrinsic (presence of impurities) fibermaterial properties
  19. 19. Imperfections in the atomic structure induce absorption by the presence of missing molecules or oxygen defects. Is also induced by the diffusion of hydrogen molecules into the glass fiber. Since intrinsic and extrinsic material properties are the main cause of absorption, they are discussed further.
  20. 20.  Intrinsic absorption is caused by basic fibermaterial properties. If an optical fiber were absolutely pure, with no imperfections or impurities, then all absorption would be intrinsic. Intrinsic absorption sets the minimal level of absorption.
  21. 21. In fiber optics, silica (pure glass) fibers are used predominately. Silica fibers are used because of their low intrinsic material absorption at the wavelengths of operation.
  22. 22.  In silica glass, the wavelengths of operation range from 700 nanometers (nm) to 1600 nm. This wavelength of operation is between two intrinsic absorption regions. The first region is the ultraviolet region (below 400-nm wavelength). The second region is the infrared region (above 2000-nm wavelength).
  23. 23. Intrinsic absorption in the ultraviolet region is caused by electronic absorption bands. Basically, absorption occurs when a light particle (photon) interacts with an electron and excites it to a higher energy level. The tail of the ultraviolet absorption band is shown in figure. The main cause of intrinsic absorption in the infrared region is the characteristic vibration frequency of atomic bonds. In silica glass, absorption is caused by the vibration of silicon-oxygen (Si-O) bonds. The interaction between the vibrating bond and the electromagnetic field of the optical signal causes intrinsic absorption. Light energy is transferred from the electromagnetic field to the bond.
  24. 24. Extrinsic absorption is caused by impurities introduced into the fiber material. Trace metal impurities, such as iron, nickel, and chromium, are introduced into the fiber during fabrication. Extrinsic absorption is caused by the electronic transition of these metal ions from one energy level to another.
  25. 25. Silica (pure glass) fibers are used because of their low intrinsic material absorption at the wavelengths of operation. This wavelength of operation is between two intrinsic absorption regions.
  26. 26. Bending the fiber also causes attenuation. Bending loss is classified according to the bend radius of curvature: microbend loss or macrobend loss.
  27. 27. Macrobend losses are observed when a fiber bend's radius of curvature is large compared to the fiber diameter. Fiber sensitivity to bending losses can be reduced. If the refractive index of the core is increased, then fiber sensitivity decreases. Sensitivity also decreases as the diameter of the overall fiber increases. However, increases in the fiber core diameter increase fiber sensitivity. Fibers with larger core size propagate more modes. These additional modes tend to be more lossy.

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