hybrid modulators

[Gurleen Kaur]

I am using hybrid modulators to suppress the FWM in dwdm system. Can anyone guide how to connect these in order??
please suggest some good papers on this topic.

[Ashu verma]

Hello Gurleen,find these papers link.use of modulators suppress FWM as shown in papers.Try to implement files and if you will have any problem,let me know then

Suppression of Four Wave Mixing in 8 Channel DWDM System … – I am browsing [Suppression of Four Wave Mixing in 8 Channel DWDM System …]. Have a look at it! https://www.google.co.in/url?q=http://www.ripublication.com/irph/ijeee_spl/ijeeev7n2_01.pdf&sa=U&ved=0CAcQFjAAahUKEwi5ns_Ys63HAhURkI4KHTwjDEc&usg=AFQjCNGtIWZ0ZcAGLGuCrG8oyj88hHCwPg

http://ieeexplore.ieee.org/xpl/login.jsp?tp=&arnumber=6424298&url=http%3A%2F%2Fieeexplore.ieee.org%2Fxpls%2Fabs_all.jsp%3Farnumber%3D6424298

http://www.researchgate.net/publication/269269401_Novel_Approaches_for_Suppression_of_Four_Wave_Mixing_in_WDM_System_Using_Concocted_Modulation_Techniques

[Gurleen Kaur]

thanks….i have implemented the paper..kindly check it for any mistakes. can u please tell the email id where i can send my file.

[Ashu verma]

Hi Gurleen you can upload here.Go to the attach file below and attach it.It may not be attached in first time.Then try using edit option and will be able to attach.Thank you

[Gurleen Kaur]

kindly check the file for mistakes…..

[alistu]

Hi Gurleen, I have run the simulation and it went well. And with a cursory look at the system configuration I did not find any problems with it. If you are sure about the configuration, then you have implemented it correctly in Optisystem.

[Gurleen Kaur]

i have implemented the paper of IEEE mentioned above

[Ashu verma]

Hello Gurleen as aalisthu said,you system works well.you can can know analyze the difference by using different modulators.which will be best to join cascadely to diminish FWM.You can also compare values of single modulator with hybrid in terms of fwm power.

[Gurleen Kaur]

okkk… how to connect these modulators—- electrical CPFSK, dual port dual drive MZ modulator, dual drive MZ modulator and AM modulator in cascade??

[Ashu verma]

For dual port MZM you van use linb modulator.for better understanding of your system let me see your base paper .Then i will get back with better suggestion

[Gurleen Kaur]

okkk..thanks

[Gurleen Kaur]

please anyone help to solve my problem mentioned above.

[Ashu verma]

check file

Attachments:

1. wave.osd

[Ashu verma]

Hello Gurleen,i have made a system as mentioned in base paper.But they havent mentioned about the parameters of ddmz and cpfsk.So i have tried to make by my own.I was astonished with the results i got from system.I took certain values by countinously varying system iterations on cpfsk freq. And found best results observed when cpfsk freq. Is half of the data rate.in your case it is 1.25 GHz .But system is correct and works fine i have used exact same components that used in base paper.Only thing is change in cpfsk parameters.Look at file and let me now if it helps and try to compare FWM powers with and without these modulators.

[Gurleen Kaur]

i have seen the file but the results are not matching with that mentioned in the paper. I have also implemented the base paper. kindly look it for any mistakes. file is attached..

[Ashu verma]

Gurleen first of all ,it is very difficult to match the results with the paper of others.Because there are some factors which can not mentioned by the author.so getting exact results are very difficult.we can only go to somewhat close to them.As far as i studied the system by varying the freq. Of cpfsk,i found that best results at 1.25 GHz and eye becomes more noisy as we increase it.If you set the freq. More thsn 1.25 GHz i think you will close to results mentioned in paper.But in paper value of ber is very high and q factor is as low as 3 .I will see your implementation and let you about either it is correct or not

[Gurleen Kaur]

file is attached….

[Gurleen Kaur]

okk. let me know my mistakes

[Ashu verma]

Your system is correct and results are very close to the paper .there were no such issue in your system .it works fine ,i have made a mistake in my last system about the use of dual drive mzm .i have used dual drive mzm insead of dual port dual drive.Your eye diagram also very much close to as shown in paper.So now you can work further on the system.
In general i have some doubts regarding the cpfsk freq. And bitspersymbol.in papwr i think they havnt written this regarding such values.from results you got and in paper it is observed that thay have used default cpfsk component with same 50 MHz value and 6 per bit.

[Gurleen Kaur]

okk thanks a lot….can u please tell based upon what criteria these modulators are chosen?? can we take combination of other modulators also??

[Ashu verma]

I think it is not good to tell to without doing literature survey regarding this concept.i will try to understand the concept.Till then i suggest you to read all the references given in your base paper .you will definitely get the concept behind it.in general fwm occures when multiple signal fed to fiber ,then there is a grneration of new wavelengths due to sum and subtration.phase matching is a key issue here and in this system they have used phase modulators to mismatch that phase in order to supress the FWM.but i will let you know exact reason and further work you can do on this work.

[Gurleen Kaur]

okk…i will try to find it out..

[Gurleen Kaur]

what value of laser linewidth we should use in this system???

[alistu]

Hi Gurleen, Since there is no mention of laser linewidth in the paper you are implementing, I would go with the defined default value or a value that I have seen in papers. For example, for CW lasers in some OFDM systems the 0.15 MHz is used and that’s what has been used in Optisystem samples.

[Gurleen Kaur]

can I take laser linewidth as zero??

[alistu]

A laser with zero linewidth is ideal and almost all of the CW lasers have a non-zero value for linewidth in practice. So if you put it as zero, your simulation will not be realistic and your results are not reliable. Unless you are assuming a very special condition (for example somehow you want to show influence of linewidth on system performance), You’d better use a non-zero value for the linewidth.

[Gurleen Kaur]

okk….i have one more doubt….in th paper it is mentioned to use dual drive MZ modulator. I should use Dual drive MZ modulator measured or LiNb MZ modulator? please clear my doubt

[alistu]

If you are implementing a certain paper (which you are) and wish to get the same results I recommend using the same components to avoid further complications, even though it may not seem to be making much difference to use similar components in some cases. I’d rather see your simulation file rather than read the paper, but I can’t find your simulation file on the page and it doesn’t matter as long as you don’t have more questions.

[Gurleen Kaur]

i have used LiNb MZ modulator for this purpose. kindly check my file is it correct or i should use Dual drive MZ modulator measured component??

Attachments:

1. wdm-mod-hybrid-50.osd

[alistu]

Dear Gurleen, I did not observe much noticeable change when I used dual drive Mach-Zehnder modulators instead of what you have used and I think the differences are merely in the mechanism they use to control the intensity. However, I would rather follow the paper when I am not completely sure about it.

[Gurleen Kaur]

ok. so which one i should use in my system??

[alistu]

As I mentioned, although it should not make difference I would go with dual port just so as to endorse my work as having exactly been implemented like the one in the paper. This is merely a suggestion since I cannot say with a hundred percent certainty about the differences being made.

Cheers!

[Gurleen Kaur]

ok..thanks

[alistu]

You’re welcome Gurleen.

[Gurleen Kaur]

i want to study the effect of dispersion value on fwm suppression. so, what values of dispersion i should take??

[alistu]

If you intend to show the effect of dispersion, you’d better use sweep iteration for several dispersion values to see how it influences FWM. This you can easily do without any former knowledge of what values make what changes. But you can have a look at papers in this regard by googling them. I suggest having a look at IEEE paper “Effect of Chromatic Dispersion on Four-Wave Mixing in Optical WDM Transmission System” which I found closer to your purpose among the papers I found by google search.

Cheers!

[Gurleen Kaur]

in the base paper, for some values the fwm power is mentioned as 0dbm whereas at this value there is no fwm products. Is this correct to mention the power as zero or as -100 dbm ?? please help it out.

[alistu]

Hi Gurleen,

I don’t know if I have actually got your question well, but 0 dBm power cannot be mentioned as zero power because it is not. If you mean to say that for 0 dBm the system in the paper has fwm products and your implementation of the same system does not, then that is the issue. I see that 0 dBm has been mentioned for the INPUT power in the paper, so you have applied a power but due to the small amount of it (or any other reason) it has not produced the result.

Regards

[Gurleen Kaur]

in the paper for high level reduction, for input power of -10 dbm the fwm products are mentioned as 0 dbm. what does it mean?? does the fwm products vanish??

[alistu]

No, it doesn’t mean they are vanished if it is mentioned so. It just denotes the amount of power they have so that you would be able to compare it with the conditions in which other input powers have been used. If you look at the table 2 (which you are referring to), you’ll see that there are other conditions in which the reduction is much more.

[Gurleen Kaur]

in the picture attached, what is the value of fwm products(dbm) ??

Attachments:

1. 

   fwm.jpg
   

[alistu]

It seems to be a relatively small amount (about -100dBm). You might want to refer to the amount in the table which is 0 dBm for input power equal to 0 dBm. But this might be a case different from the one whose results are there in the table. This might be the same case as one of the simulations in the figure 11, for example, whose FWM power level is around -100 dBM for input power equal to 0 dBm.

[Gurleen Kaur]

okk. but in the paper i am reffering -100 dbm is taken as 0dbm. what does it means??
here is the paper….
https://www.google.co.in/url?q=http://www.ripublication.com/irph/ijeee_spl/ijeeev7n2_01.pdf&sa=U&ved=0CAcQFjAAahUKEwi5ns_Ys63HAhURkI4KHTwjDEc&usg=AFQjCNGtIWZ0Zc

[alistu]

I am also referring to the same paper. I don’t think that’s true. In the same paper in all the tables, there are both 0 dBm and -100 dBm powers there. Otherwise, could you specifically address the part of the paper in which according to your statement such an assumption has been made?

[Gurleen Kaur]

in table 2 for input power 0 dbm the fwm power is 0. but in the figure 9 the spectrum is shown where fwm power is -100 dbm for input power 0 dbm.

[alistu]

That’s right. And it can be seen that in figure 11 the FWM power for 0 dBm input power is near -100 dBm. So I am guessing (and it’s just a guess) that spectrum in figure 9 has been shown with system settings similar to one of the cases in figure 11, and not with the system settings whose results are there in table 2. Only this way makes sense to me. If the authors want to take 0 dBm as -100 dBm, then why not using the -100 dBm itself?

[Gurleen Kaur]

okkk… so i can mention it as -100 dbm in my work??

[alistu]

I don’t think you can do such a thing. I have explained in my previous comments why. You should just know figure 9 necessarily does not relate to the table 2, it might be referring to figure 11. That’s all I can tell.

If you are attributing figure 9 to figure 11 (and not to table 2), then you can assume that FWM power is -100 dBm for “input power = 0 dBm”. In this case, you are not assuming 0 dBm = -100 dBm.

[gaganpreet Kaur]

does modulator used not depend on data rate i mean performnace will improve using advance modulation formats wrt to FWM at high data rates. also for all dig=fferent modulation formats suggested/ used are we not limited in optisystem to few channel system only

[alistu]

You’re right. The modulation scheme that is deployed for the system will definitely have effects on the system performance regarding unwanted physical effects such as chromatic dispersion and so on. The more successfully the modulation fights these effects, the longer the transmission line or the higher the bit rate can be.

[Ashu verma]

Hi! Gagan
Since you are working on FWM, then for sure there are effects of using different modulation formats on FWM .You can find lot of articles on this particular topic.Data rate is independent of FWM as reported in most of the articles.Advance modulation formats are bandwidth efficient and less prone to the dispersion effects due to phase shift in consecutive bits.This in turn increase total transmission length of the system .
Take a look at these papers
http://ieeexplore.ieee.org/xpl/login.jsp?tp=&arnumber=6518625&url=http%3A%2F%2Fieeexplore.ieee.org%2Fxpls%2Fabs_all.jsp%3Farnumber%3D6518625
http://airccse.org/journal/ijdps/papers/1111ijdps25.pdf
http://www.ijera.com/papers/Vol4_issue1/Version%202/V4102176181.pdf
https://www.google.co.in/url?sa=t&rct=j&q=&esrc=s&source=web&cd=3&cad=rja&uact=8&ved=0CC8QFjACahUKEwjo8ra654XIAhWQGY4KHdJJBQY&url=http%3A%2F%2Fwww.aast.edu%2Fpheed%2Fstaffadminview%2Fpdf_retreive.php%3Furl%3D53905_66_80_Paper%252083.pdf%26stafftype%3Dstaffpdf&usg=AFQjCNEi1HwaevSXDY8D8_-pzXrkc3ymxQ&bvm=bv.103073922,d.c2E

[gaganpreet Kaur]

Thank u so much alsitu and Sam . yes, Sam i am working on four wave mixing supression in WDM systems .thanks for sharing important papers on this topic .i am really very thankful.

[Abhishek Shrama]

Hi gaganpreet,Since you are working on FWM ,paper attached by Sam are very helpful.Could you please let me know,what suppression methods you are working on? According to my knowledge ,many papers already been proposed on FWM suppression by using advanced modulation formats which is clear from attached links above.I am working in the same area,so sharing knowledge with one another on this topic may end up with fruitful results.

[gaganpreet Kaur]

hi abhishek i have just started exploring use of hybrid modulators for FWM suppression but dont have much knowledge. yes i have studied so many supression methods in lieratue but of recent not much work(quality-authenticated nby IEEE or OSA) was found so i dropped it. justout of intellectual quest i have started studying modulation formats for FWM suppression

[Abhishek Shrama]

IF this is the case than you can go for optical phase conjugation along with FBG and DCF to suppress FWM.Because i have seen work on hybrid modulators and modulation formats.Also on OPC ,but you may try different combinations for the control of FWM in system.
Here i have given a link for article from optik
http://www.researchgate.net/publication/261716528_Suppression_of_four_wave_mixing_in_wavelength_division_multiplexed_system_with_hybrid_modules
Kindly study it and let me know if it helps

[gaganpreet Kaur]

Hi Sam pls could be tell me how to plot FWM power vs frequency/wavelength in optisystem. i mean i want to show the idler power against the their frequency for a WDM system.

[Ashu verma]

Hi! Gaganpreet
Sorry i was busy in my research work and hardly get a time now a days to do reply on forum more frequently.here if you want to see the fwm signal ,it can be easily seen from OSA.However if you want to plot then you need to select one parameter for example input power on x axis and fwm power on y axis.In this way you can plot fwm signal power vs input power and even add signal power vs input power.Is this your query ,because i dont get how you asked to plot fwm vs freq.
In case you have seen this type of plot then attach screen shot and this will be more clear to me.

[gaganpreet Kaur]

Hi Sam same here i am too engrossed in my research and need to make some submissions too. right now alilttle help from u or alistu can be gr8 for me. i get BER and Q factor as high as 364 at 2.5 Gbps but same system when simulated at 10 Gbps or 40 Gbps shows no results. what changes shoul i make to my design … to achieve required BER .
secondly i want to analyse effect of a modulation format on FWM . can i plot FWM power .if yes how

Regards and pls ur help can make huge huge difference to my results.

[alistu]

Hi Gaganpreet,

Can you please upload the latest osd file you are working on, so that the necessary changes be made to it? Thank you.

[gaganpreet Kaur]

Hi alistu sorry i was occupied with my research work. i am attaching the file . i have made some changes so i am getting BER of order of 10-19 but as i increase my bit rate from 10 gbps to 40 or 100 gbps results vansih. my sincerest request is to have BER at high data rates what changes are needed to be made. With Regards.

Attachments:

1. ber.osd

[alistu]

Hi Gaganpreet,

The fact that your system does not maintain the acceptable results for higher bit rates or the increased fiber length does not necessarily denote wrong system implementation. But I am guessing in your case, you forget to change the channel spacing and the WDM channel bandwidth according to the bit rate each time you change it. Please change the corresponding changes as well.

[gaganpreet Kaur]

hi alistu i did’nt get what changes be made if i chabge my bit rate i don’t want to change channels spacing i actually want to implement 16 X 100 Gbps system with 25GHz channel spacing…is it not possible . if i dnt get BER result how do i prove my system will be feasible

[alistu]

Theoretically, increasing the bit rate would cause an increase in the changes made to the signal at the time unit. In other words, it will cause the frequency of the signal to rise and therefore, the signal would take up more bandwidth. That’s why you have to change the channel spacings according to the bit rate you choose.

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