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(joined April 2014)
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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

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Responses (18):

    • #14800
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      Heitor Galvao
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      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

      Attachments:
    • #14802
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      Heitor Galvao
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      Someone has a tip? What can be?

    • #14804
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      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 fiber

      D(SMF)*L(SMF)+D(DCF)*L(DCF)=0

      +1
    • #14807
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      Heitor Galvao
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      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

    • #14812
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      Damian Marek
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      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

      • #14818
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        Heitor Galvao
        Participant

        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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        • #14823
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          Damian Marek
          Participant

          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).

        • #14824
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          Heitor Galvao
          Participant

          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

    • #14825
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      Heitor Galvao
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      See how long it takes

    • #14827
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      Ravil
      Participant

      Hi Heitor, what are the parameters of your PC: RAM and CPU (the one you are using for your project)?

      • #14828
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        Heitor Galvao
        Participant

        Installed memory (RAM): 2 GB (used: 1, 87GB)
        my project is using disk size of 0.98 MB

    • #14829
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      Heitor Galvao
      Participant

      my project is using disk size 1.08 MB, correcting

    • #14830
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      Heitor Galvao
      Participant

      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?

      Attachments:
    • #14877
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      Heitor Galvao
      Participant

      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?

    • #14880
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      Damian Marek
      Participant

      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

      • #14891
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        Heitor Galvao
        Participant

        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

    • #14897
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      Heitor Galvao
      Participant

      Hi Damian, forgiveness for the mistake I typed the wrong project are ok, follow table in pdf, thanks Damian

      • #14924
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        Damian Marek
        Participant

        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.

        • #14931
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          Heitor Galvao
          Participant

          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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