Losses

[Ankita Sharma]

Hello Everyone,

Can someone specify the main striking difference i.e the distuinguishing between linear scattering loss and non linear scattering loss in the case of optical fibers? Also I have another query, Are these scattering losses in optical fibers proportional to frequency of light or not ? Someone please provide me to the point answer….

Thanks and Regards

[SAHIL SINGH]

Hi Ankita,

As far as these scattering losses are concerned,the main difference between the two is the is phycical nature of the scattering mechanisms….Linear scattering losses which are also called Rayleigh scattering losses, are due to microscopic variation in the material of the optical fiber where as the Non-linear Scattering losses may be regarded as the modulation of light through thermal molecular vibrations within the fiber… Hope this helps

Regards
Sahil Singh

[aasif bashir dar]

hi ankit,
Linear scattering losses, which also called Rayleigh scattering losses, are due to microscopic variation in the material of the fiber: unequal distribution of molecular densities or atomic densities leads to these losses. Rayleigh scattering losses proportional to frequency of light to the 4th power.
Non-linear Scattering represented mainly by Stimulated Brillouin Scattering (SBS) or Stimulated Raman Scattering (SRS) may be regarded as the modulation of light through thermal molecular vibrations within the fiber. SRS is similar to SBS except that high frequency optical phonon rather than acoustic phonon is generated in scattering processes. Phonon – collective excitation in a periodic arrangement of atoms or molecules in solid.
High irradiance/intensity of light beam is the main reason of non-linear scattering to occur.

with regards

[SAHIL SINGH]

Hi Asif Bashir,

Very rightly pointed out by you that Rayleigh scattering losses are proportional to frequency of light to the 4th power…. Thanks for the information

Regards
Sahil Singh

[Ankita Sharma]

Hi all,

Thanks all for your reply…

Regards
Ankita Sharma

[umer syed]

hi all,

the striking difference is;;
In linear scattering, attenuation occurs when optical power is transferred from one mode to another keeping frequency unaltered.
Non linear scattering occurs when frequency is changed during optical power transfer.

thus change in the frequency conversion is key concept to differentiate the two effects
with regards

[SAHIL SINGH]

Hi Ankita Sharma,

You are welcome… Hope that you got the information what you were looking for…

Regards
Sahil Singh

[Atul Sharma]

you are welcome Ankita.

[Ranjeet Kumar]

Hi Ankita,
In linear scattering, attenuation occurs when optical power is transferred from one mode to another keeping frequency unaltered. There are two categories in linear scattering. They are Rayleigh scattering and Mie scattering. Rayleigh scattering is the main loss mechanism in the visible range. It is proportional to the fourth power of the operating wavelength. Rayleigh scattering loss can be minimized by choosing longest possible operating wavelength. If the size of the defect is greater than one-tenth of the wavelength of light, the scattering mechanism is called Mie scattering. Non linear scattering occurs when frequency is changed during optical power transfer. The two types of nonlinear scattering are stimulated Brillouin scattering and stimulate Raman scattering. Stimulated Brillouin scattering is a cause of concern in long distance systems, in wavelength division multiplexing (WDM) systems and remote pumping of an erbium doped fiber amplifier (EDFA) through a separate optical fiber. Stimulated Raman scattering creates problems in wavelength division multiplexing (WDM) systems.

[Ranjeet Kumar]

scattering centers which are much smaller than the wavelength of the light. Under such circumstances, the scattering occurs with amplitudes which are proportional to the in-coming amplitude, to the fourth power of the inverse wavelength, and to 1 + cos2 θ, where θ is the scattering angle. Forward and backward scattering (θ = 0 and θ = π, respectively) are equally strong.

Scattering at larger centers can be described by Mie scattering theory (named after Gustav Mie). Here, the characteristics are different; for example, the scattering amplitudes are stronger for forward scattering, and the wavelength dependence is different.

Scattering centers for Rayleigh scattering can be individual atoms or molecules. However, one can also describe Rayleigh scattering in the atmosphere, for example, as resulting from microscopic density fluctuations, which are caused by the random distribution of molecules in the air.

[Ubaid Bhat]

hi ankita ..
The main difference is phycical nature of the scattering mechanisms.
Linear scattering losses, which also called Rayleigh scattering losses, are due to microscopic variation in the material of the fiber: unequal distribution of molecular densities or atomic densities leads to these losses. Rayleigh scattering losses proportional to frequency of light to the 4th power.
this topic has been discussed by one of the forum master and he has given a very good explanation of the same. i am attaching that link for your reference.hope you will get some help from that.
optiwave.com/forums/topic/difference-between-linear-and-nonlinear-scattering-loss/
with regards

[Ubaid Bhat]

Non-linear Scattering represented mainly by Stimulated Brillouin Scattering (SBS) or Stimulated Raman Scattering (SRS) may be regarded as the modulation of light through thermal molecular vibrations within the fiber. SRS is similar to SBS except that high frequency optical phonon rather than acoustic phonon is generated in scattering processes. Phonon – collective excitation in a periodic arrangement of atoms or molecules in solid.
High irradiance/intensity of light beam is the main reason of non-linear scattering to occur.
with regards

[varinder singh]

helo dear…..losses are present everywhere …..optical fibres cables also have losses …..i think u got the answer of ur question ….i agree with sahil singh…..

[Ankita Sharma]

Hi everyone on the forum,

Thank you all for providing me with your valuable responses and sparing your time to my query.. I am glad you all responded and I got the answer what I was looking for… Appreciate your efforts

Thanks and regards
Ankita Sharma

[Rajguru M. Mohan]

Hi Ankita,
As we have two types of scattering losses. They are linear scattering and nonlinear scattering.
In linear scattering, attenuation occurs when optical power is transferred from one mode to another keeping frequency unaltered.
There are two categories in linear scattering. They are Rayleigh scattering and Mie scattering.
Rayleigh scattering is the main loss mechanism in the visible range, it is linear scattering of light at scattering centers which are much smaller than the wavelength of the light. Under such circumstances, the scattering occurs with amplitudes which are proportional to the in-coming amplitude, to the fourth power of the inverse wavelength
It is proportional to the fourth power of the operating wavelength.
Rayleigh scattering loss can be minimized by choosing longest possible operating wavelength.
If the size of the defect is greater than one-tenth of the wavelength of light, the scattering mechanism is called Mie scattering.
Non linear scattering occurs when frequency is changed during optical power transfer. The two types of nonlinear scattering are stimulated Brillouin scattering and stimulate Raman scattering. Stimulated Brillouin scattering is a cause of concern in long distance systems, in wavelength division multiplexing (WDM) systems and remote pumping of an erbium doped fiber amplifier (EDFA) through a separate optical fiber. Stimulated Raman scattering creates problems in wavelength division multiplexing (WDM) systems.

Thanks

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