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Laser used in WDM transmitter

Home › Forums › SYSTEM › Laser used in WDM transmitter

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    • January 8, 2016 at 6:43 am #29065
      Marvi grover
      Participant

      i am attaching a system designed in optisystem. kindly take a look at the transmitter part and let me know if it is a valid system. Is it possible to use a single continuous wave laser as the source(for a WDM system), split its output using a fork and then use MUX for wavelength division multiplexing??. also here the modulator is used after the MUX. will this system produce a multiplexed output.

      i shall be really grateful for any help provided

      thankyou

    • January 8, 2016 at 1:30 pm #29073
      alistu
      Participant

      Hi Marvi,

      You’d better use CW laser array as the laser source. Also, you should use a separate PRBS generator for each user, otherwise it negates the reason for using WDm in the first place. I suggest you use WDM transmitter component in transmitters library, which contains both PRBS generation part and the optical power source.

      Regards

    • January 8, 2016 at 10:07 pm #29075
      Marvi grover
      Participant

      Hi Alistu,
      thank you so much for replying.

      Actually i saw this system in a research paper published in Springer. but i was not convinced with the working of this system.there it is shown as an improvement of the system which uses a laser array, in order to reduce its complexity, the author used a single laser.
      i wanted to further optimize this system. so should i continue with this system or should i use the array only??

      i have attached the paper for your reference. please have a look once and suggest the i should work on this or not.

      • January 9, 2016 at 4:32 am #29078
        alistu
        Participant

        Thank you for the paper. In the system design, a fork has been used instead of power splitter at the transmitter. Since there is no such component in reality, I believe it is like using an array of lasers or a laser with much more power together with a splitter. So if you want to implement system II of the paper, you should use a splitter and a laser who has 20dB power at each output branch of the splitter.

        • January 9, 2016 at 4:46 am #29080
          Marvi grover
          Participant

          okk. Thanks Alistu
          but i have one more doubt, the power splitter would split the laser power into multiple ports but the wavelength of light coming out from each port of the splitter would be same because we are using one laser as the source. so how will wavelength division multiplexing happen beacause we need different wavelengths for WDM.
          i also want to know if there is a multiwavelength laser available in optisystem???

          thankyou

        • January 9, 2016 at 5:57 am #29083
          alistu
          Participant

          You’re welcome. As I mentioned in my first reply, CW laser array consistes of several lasers each with a different wavelength from others and can be used in WDM systems. I am not quite sure about what has been done in the paper to produce multiple wavelengths (if actually they have been produced), so can you please upload your implementation of the paper so as to examine it?

        • January 9, 2016 at 6:48 am #29085
          Marvi grover
          Participant

          okk. I am attaching the file. please check if the wavelength division multiplexing is actually happening. the BER analyser might show a perfect eye diagram because i have made the component noises negligible. The actual paper has been implemented in optisystem 11.

        • January 9, 2016 at 7:43 am #29088
          alistu
          Participant

          Thank you for the attachment. There is no change in the signal in the output of the multiplexer when compared with laser spectrum, except for the fact that its power has increased due to fork being used (which multiplies the power as we discussed). I don’t really understand why the author has even used WDM for this purpose. BTW, The impact factor of the journal is around 0.6, so I wouldn’t trust the results so much.

    • January 11, 2016 at 8:22 pm #29138
      Marvi grover
      Participant

      Hi Alistu. .. I got some justification for the above discussed system. Actually the MUX used in optisystem has inbuilt filters at each of its input channels which have some central frequency(each channel has a different central frequency). so each input of the mux filters only that particular frequency and allows it to go further. so in this way the wavelengths are seperated.

      but i wanted to know if the Laser used in the system emitted only one fixed frequency or it emits a small band of frequencies???

      Regards

      • January 12, 2016 at 6:18 am #29149
        alistu
        Participant

        Even though the parameters you mentioned have in-built filters and their spacing can be determined and so on, if you use OSA visualizers to see the spectrum after the laser and after the MUX, you will notice there is absolutely no change in the spectrum except for the fact that the power has increased due to the reason I mentioned before.

    • January 12, 2016 at 12:13 pm #29158
      Marvi grover
      Participant

      ok. Thanks a lot Alistu.

    • January 9, 2016 at 8:34 am #29092
      Marvi grover
      Participant

      ok . again thanks a lot alistu.
      i am really grateful for your help. one last question… the ‘fork’ present in the optisystem is available practically or not???

    • January 9, 2016 at 8:51 am #29093
      alistu
      Participant

      You’re welcome Marvi. The fork system copies the input and sends it to the output. So if the total output power is measured, it is more than the input power. This component is not based on a real component, but it may be useful in the simulations, as you can see it being used in OptiSystem samples.

      Regards

    • January 9, 2016 at 10:08 am #29094
      Marvi grover
      Participant

      ok.. Thanks A lot Alistu .

    • January 9, 2016 at 11:43 am #29095
      alistu
      Participant

      You’re welcome. Another strange thing about the implementation in the paper is the fact that one PRBS generator is used. So I don’t think using an access method such as WDM is of any use, since only one user is available here and it is a kind of point-to-point communication. I thought this was worth mentioning because it is also something you should consider beside laser frequency.

      Regards

    • January 9, 2016 at 9:25 pm #29101
      Marvi grover
      Participant

      yes Alistu, even i had the same doubt. multiplexing is being done before modulation.
      i am trying to use some new components to improve the system.

      i am not able to find out the 32 bit version of optisystem 14 or 13 or 12 for the 30 day trial use.
      as my laptop is 32 bit, so 64 bit version is not getting installed on it. can you please suggest me how to download the 32 bit version.

      Regards

    • January 10, 2016 at 3:25 am #29107
      alistu
      Participant

      Unfortunately, I don’t know what can be done about it, except for what I have suggested in your other topic. Of course, you can reinstall a 64-bit windows operating system to be able to use the current version. 64-bit version makes better use of RAM than 32-bit, it is generally better to use that if possible.

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