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Design of a Niquist-filtered 100 Gbps PM-DQPSK (DP-DQPSK) transmitter

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(joined December 2014)
Participant

Hello everyone,

I have a problem in design of a Niquist-filtered 100 Gbps PM-DQPSK transmitter. I tried to use the optical raised-cosine filter to shape pulse of the generated PM-DQPSK signal, but it failed. I also tried to use the electrical raised-cosine filter to shape the driven NRZ signal, then to generate narrowband (25GHz) optical PM-DQPSK signal, but it failed either. Is there someone can tell me how to design a Niquist-filtered 100 Gbps PM-DQPSK transmitter? Thank you very much!

Best regards,

Responses (4):

    • #16585
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      xiaoyong chen
      Participant

      Hello everyone,

      I have a problem in design of a Niquist-filtered 100 Gbps PM-DQPSK transmitter. I tried to use the optical raised-cosine filter to shape pulse of the generated PM-DQPSK signal, but it failed. I also tried to use the electrical raised-cosine filter to shape the driven NRZ signal, then to generate narrowband (25GHz) optical PM-DQPSK signal, but it failed either. Is there someone can tell me how to design a Niquist-filtered 100 Gbps PM-DQPSK transmitter? Thank you very much!

      Best regards,

    • #16614
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      Damian Marek
      Participant

      Hello,

      I fixed up your project and got it working there was problems with the transmitter!

      Be careful when copying components from example files into a new project, because sometimes they will be referencing parameters that might not exist in your layout. For example I had to add a layout parameter called “rolloff” to your project so that the M-ARY Raised Cosine Pulse Generator would give reasonable results.

      Moreover, careful consideration of the biasing and driving of MZM’s is needed. I added an electrical gain and bias to the inputs so I could copy close values from the example file. Then I played with the gain until I got good results. It is also possible to modify the gain and bias inside the parameters of the MZM, but I prefer explicitly setting the gain and bias before and only changing the Vpi of the MZM.

      Regards

      +1
      • #16620
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        xiaoyong chen
        Participant

        Dear Damian,

        Thank you very much for your help. Now the program works and I have successfully changed the bit-rate to 100 Gbps.

        Thank you!

      • #16673
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        xiaoyong chen
        Participant

        Hi Damian,

        Sorry for bothering you again. I have another question about Nyquist-filtered QPSK signal. In the last file you attached to me the Q-factor of the Nyquist-filtered QPSK is only 7, is it possible to improve the Q-factor to more than 10? Thank you!

        Best regards,
        Chen

    • #16619
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      xiaoyong chen
      Participant

      Dear Damian,

      Thank you very much for your help. Now the program works and I have successfully changed the bit-rate to 100 Gbps.

      Thank you!

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