- This topic has 7 replies, 4 voices, and was last updated 9 years ago by Alessandro Festa.
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October 9, 2015 at 9:30 am #26090kollParticipant
Signal Degradation in optic fiber are caused by noise,attenuation and dispersion?
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October 9, 2015 at 9:35 am #26091alistuParticipant
Hi Koll,
Yes! And also by the nonlinear effects. When the optical power injected into the optical fiber is high, these effects show a considerable effect. You might have heard of self-phase modulation (SPM), cross-phase modulation (XPM) and the four-wave mixing (FWM) as some examples of nonlinear effects.
Regards
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October 9, 2015 at 9:37 am #26092kollParticipant
Hi Alistu but from the link here I googled.
why they only mentioned attenuation and dispersion?
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October 9, 2015 at 9:47 am #26095alistuParticipant
On the second page from the file you have uploaded, it can be seen that the transmission effects are divided into two categories, one being nonlinear effects. And the three examples I have mentioned are also among the nonlinear effects. I don’t know why it has not been mentioned on the first page, but on the second page those two factors are also mentioned.
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October 9, 2015 at 9:51 am #26096kollParticipant
So noise are consider as non linear effect?
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October 12, 2015 at 2:42 am #26237Alessandro FestaParticipant
Noise is usually considered a linear effect (eg: ASE from optical amplifiers). Anyway, there are propagation models where the noise itself incorporates both linear and nonlinear effect, like the GN-model.
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October 9, 2015 at 10:16 am #26097alistuParticipant
I believe both nonlinear effects and the dispersion effect (which may degrade signal by causing inter-symbol interference) can be considered as noise in the transmission line. I don’t know if in the above lecture the nonlinear effects have been considered as the noise factor in the optical fiber.
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October 10, 2015 at 1:31 am #26126gaganpreet KaurParticipant
i would like to add non-linear effects become significant at high powers which are required for long distance transmission. also in case of multi-channel systems as the channel spacing id reduced non-linear effects cannot be ignored. rather for WDM systems XPM and FWM non-linear effects are most deteriorating. SPM( Single Phase modulation) is significant for single channel systems only.
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