- This topic has 18 replies, 4 voices, and was last updated 10 years ago by Heitor Galvao.
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November 3, 2014 at 11:20 am #14800Heitor GalvaoParticipant
Good morning my project this in annex, in the signal generator Back2Back is working, what I don’t understand is when I put the link of more fiber amplifier to compensate, and make a compensation of dispersion decreasing fiber length for 40 km, and placing negative dispersion, and don’t understand why the signal is not being generated, you can check out my project to view
I am using optisystem 7 -
November 3, 2014 at 11:23 am #14802Heitor GalvaoParticipant
Someone has a tip? What can be?
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November 3, 2014 at 11:41 am #14804Jaffar Emad KadumParticipant
Use the following parameters for Dispersion compensating fiber:
Dispersion= -80
Loss= 0.5
Dispersion slop =-0.03
and use the following eqaution to find the length of Dispersion compensating fiberD(SMF)*L(SMF)+D(DCF)*L(DCF)=0
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November 3, 2014 at 12:23 pm #14807Heitor GalvaoParticipant
When the transmitter is placed on fiber link + amplifier (DCF and SMF) really doesn’t work, nothing appears on the BER analyzer, while in back2back, the signal is generated correctly
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November 3, 2014 at 2:06 pm #14812Damian MarekParticipant
The eye diagrams in your attached project are not really open, so I made changes to the first channel to get better results. The symbol rate was too high for the optical receiver. Even though overall you are correct about the symbol rate. The symbol rate over each channel is equal to the bit rate.
The other aspect of your project that I saw was that the signals have incredibly high powers >100 W! Typically, in a optical system the powers are around 5-10 mW. The nonlinearities in the fiber are causing the distortion of the signal, which DCF cannot compensate for. I’m also pretty sure the fiber’s would get pretty hot at these powers. Can you lower the power of your frequency comb generator? In Transmitters Library/Optical Transmitters there is a WDM Transmitter component that could possible replace your frequency comb generator.
Regards
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November 3, 2014 at 3:02 pm #14818Heitor GalvaoParticipant
Thanks Damian, remarks now change the frequency of 151.1 THz to 191.2 THz and really I could see better, now the signal is propagating in the fiber, but not get out of the first loop, if I put two laps in the control loop for example. You can check please
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November 3, 2014 at 4:35 pm #14823Damian MarekParticipant
You are running into a problem someone else on the forum is experiencing. It has to do with the extremely large (unrealistic) optical powers in your design. The numerical model used to simulate the nonlinearity takes longer for higher power signals (more experienced nonlinearity).
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November 3, 2014 at 4:54 pm #14824Heitor GalvaoParticipant
Excellent Damian, can be a path to what can resolve, you can direct me to the post, who is working with this problem so I can take a look
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November 3, 2014 at 5:40 pm #14825Heitor GalvaoParticipant
See how long it takes
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November 3, 2014 at 6:52 pm #14827RavilParticipant
Hi Heitor, what are the parameters of your PC: RAM and CPU (the one you are using for your project)?
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November 3, 2014 at 10:25 pm #14828Heitor GalvaoParticipant
Installed memory (RAM): 2 GB (used: 1, 87GB)
my project is using disk size of 0.98 MB
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November 3, 2014 at 10:31 pm #14829Heitor GalvaoParticipant
my project is using disk size 1.08 MB, correcting
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November 3, 2014 at 11:33 pm #14830Heitor GalvaoParticipant
Actually the problem is non-linear effects, I disabled the nonlinear effects, the fiber properties and the signal has spread in the link as you can see in the table in annex. Now I wonder how to combat this nonlinear effects?
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November 4, 2014 at 12:39 pm #14877Heitor GalvaoParticipant
Hello Damian, I managed to reduce the power now to less than 10mW, as power in the annex, and already has an eye diagram, now why does not propagate in the fibre link?
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November 4, 2014 at 1:03 pm #14880Damian MarekParticipant
The problem was with the reference wavelength and the numerical method wavelength range. In the fibers set the reference wavelength to around 1982 nm and in the Numerical tab set the wavelength range to something like 1700 nm to 2100 nm. The wavelength you are using is a little far from the default values a lot of the components will assume, so you just need to make sure that the are set correctly. Check the project file (OptiSystem 13) attached.
You will also need to set the noise bins to a correct value in the components that create them. For example the optical amplifiers in the comb generator.
Regards
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November 4, 2014 at 3:31 pm #14891Heitor GalvaoParticipant
Very good Damian, made the necessary changes and actually worked, didn’t show zero in five laps, the doubt that I still own is following the value of revou (BER) for the second channel, is to decrease the measure increases the number of laps, and that doesn’t happen. Gives the first lap for the second occurs a surge of revou (BER), you know what can be?
Follow PDF and palette to confer
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November 4, 2014 at 8:13 pm #14897Heitor GalvaoParticipant
Hi Damian, forgiveness for the mistake I typed the wrong project are ok, follow table in pdf, thanks Damian
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November 5, 2014 at 10:03 am #14924Damian MarekParticipant
I’m not sure what the Layout parameter “Symbol” is you made, but if it is for symbol rate then I think it is incorrect. I believe I changed this in an earlier file you sent me. The filter’s bandwidth in the Optical Receiver depend on this correct value, which should be 10 Gbps, since you are using a bit rate of 10 Gbps and the modulation scheme is OOK-RZ.
I’m not sure why but the Optical Receiver is not finding the correct decision instant so I set it manually in the first receiver to 0.5 bits. It seems to be giving accurate results now, although the BER is low.
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November 5, 2014 at 11:27 am #14931Heitor GalvaoParticipant
Hello Damian can you show me the screenshot of the RZ-OOK modulation, I’m in I can’t open 12 optisystem your edited palette
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