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Generation of RZ-DQPSK modulation for different duty cycles

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(joined March 2014)
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Hi,

How to generate different duty cycles(40%,50%,60% etc) of RZ for DQPSK Modulation?
If i used example DQPSK Signal 33 percent.osd file,which parameter has to be changed to get different duty cycles of RZ(DQPSK modulation)?
Otherwise is there any another way to get different duty cycles(like directy using RZ driver instead of extra MZM modulator)?

How can set the LiNb MZ Modulator settings(like voltage values) w.r.t DQPSK modulation?

Please help me with complete details.

Responses (35):

    • #14668
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      Hi,

      How to generate different duty cycles(40%,50%,60% etc) of RZ for DQPSK Modulation?
      If i used example DQPSK Signal 33 percent.osd file,which parameter has to be changed to get different duty cycles of RZ(DQPSK modulation)?
      Otherwise is there any another way to get different duty cycles(like directy using RZ driver instead of extra MZM modulator)?

      How can set the LiNb MZ Modulator settings(like voltage values) w.r.t DQPSK modulation?

      Please help me with complete details.

    • #14721
      Profile Photo

      To generate RZ signal extra MZM modulator and sine wave generator is used in many examples and papers.
      Why can’t use directly RZ pulse generator instead of extra MZM modulator?

      Please provide any explanation for the cause.

      Thanks
      Siva Rama Krishna

      • #14743
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        Damian Marek
        Participant

        A simple way could be to use an Optical Amplitude modulator (same folder as the mach zehnder modulator’s) and modulate with a Sine Pulse generator. I’m not sure about making different duty cycles with MZM’s directly. Do you have an article that I could look at?

        Regards

    • #14741
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      Please reply

    • #14770
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      Please find the attached paper

      Attachments:
      • #14888
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        Damian Marek
        Participant

        Attached is a direction you could go to get these different duty cycles. I am not sure what type of pulse they used in the paper (rectangular?) but I used a higher order Gaussian to emulate a LiNBO3 modulator output. You can change the width of the gaussian pulse generator to get different duty cycles.

        Cheers

        +2
    • #14957
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      Hi Damian,
      Thank you for reply.And Your solution gives the way generating different duty cycles for RZ.That’s clear.
      But my question is why can’t use RZ pulse generator(paremeter: Duty cycle) to get RZ with different dury cycles.Why can’t use RZ pulse generator instead of NRZ pulse geneartor in DQPSK Signal 33 percent.osd?
      If possible with RZ pulse generator,then we can use directly “duty cycle” parameter of RZ pulse generator.

      Please provide your assistance.
      Thanks in Advance
      Siva Rama Krishna

    • #14960
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      Damian Marek
      Participant

      Yes absolutely. Simply replace the Gaussian pulse generator with an RZ pule generator in my project and it will work.

    • #15034
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      Ibn Aziz
      Participant

      Hi Damian Marek

      thanks for ur kind response and sharing file of high order gusian pulse carving.

      But dear i need optical pulses at the output through any mean by using CW lase source at the input.

      For that i need ur help and the paper about which i ref u is using the same idea in which he used CW laser+RF signal and modulat it by using 4 MZM modulators.

      I did the same i got pico secnd pulses.

      But problem is that i need

      Time period of optical pulses = 7.8125 nsec
      pulse width of optical pulses = 1 nsec

      which i am not getting.

      if u know any way for getting such pulse plz share.

      i am also attaching figure of such pulse.

      regards

      Attachments:
    • #24569

      I need to generate a DQPSK signal at 10Gbps bitrate, please provide me with steps.

      • #24573
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        alistu
        Participant

        Please see if my answer in your DQPSK topic helps.

    • #24632
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      gaganpreet Kaur
      Participant

      Hi Damian pls it would be gr8 help if you could send me the snapshot of highordergaussianpulsecarving.osd design file. actually i have optisystem 7.0 and unable to open the file and i need the modulation format for high fat rate transmission.
      Thanks in advance , pls help
      Regards

      • #24637
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        alistu
        Participant

        Hi Gaganpreet,

        I have attached a snapshot of the system Damian has attached at your request. Since it’s the weekend, I figured you might be waiting for a while for it otherwise.

        Regards

        Attachments:
        +2
    • #24667
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      gaganpreet Kaur
      Participant

      Thank u so much alistu i was seriously waiting for it coz i need to understand difference in output BER with NRZ, RZ and DP-QPSK modulation at 100 Gbps. thanks again

    • #24695
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      Ashu verma
      Participant

      Gagan screen shot attached by alistu is from latest version.There is dp Qpsk transmitter and i dont think exact transmitter is there in optisystem 7.

    • #24696
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      alistu
      Participant

      You’re welcome Gaganpreet. I am glad it saved you some time.

      The screenshot I have attached at Gaganpreet’s request belongs to the highordergaussianpulsecarving.osd file Damian has uploaded in this page, which is attached on reply #14888.

      Cheers!

    • #24712
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      gaganpreet Kaur
      Participant

      Sam we are using QPSK to get DP-QPSK so its there in optisystem 7.0 and was gr8 help to me

      • #24721
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        Ravil
        Participant

        Hello Gaganpreet,
        I am not sure that you noticed it but I just want to mention to you that if you have modeled you QPSK scheme already (as you said in the previous comment) you can convert it to DP-QPSK by adding polarization controller. When I was working on it, I used example http://optiwave.com/applications/100-gbps-dp-qpsk-system-with-digital-signal-processing/ and its references.

      • #24733
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        alistu
        Participant

        Hi Gaganpreet, I think you can easily find out if the component is there in Optisystem v.7. If the aforementioned block exists in version 7, you can find it in transmission library (or any other name it has in version 7), where other coding schemes (such as QAM and PSK) are there.

    • #24770
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      gaganpreet Kaur
      Participant

      hi alsitu we have OQpsk in optisystem 7.0 and not QPSK. can OQPSK be used to generate DP-QPSK.

      • #24776
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        alistu
        Participant

        Can you please tell me if the PSK coding component is there in Optisystem v.7? If it is available, then by choosing the “bits per symbol” parameter as 2, you can have QPSK. Other than that, QPSK and 4-QAM are the same. So by choosing QAM modulator and changing “bits per symbol” to 2, you can have QPSK coder/decoder.

    • #24790
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      gaganpreet Kaur
      Participant

      Thank you so much alsitu. if i need to use DP-QPSK for a wdm system do i need to apply the modulation described in this forum to each channel separately where we have a CW laser as input source as input at one particular wavelength.

      • #24799
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        alistu
        Participant

        You’re welcome Gaganpreet. Yes, in a WDM system where the channels are seperated from one another by frequency(wavelength), you would apply the coding scheme used to every frequency channel. You may have used a separate CW laser for each channel, or the WDM CW laser as source to all channels.

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