Generation of RZ-DQPSK modulation for different duty cycles

[siva rama krishnaParticipant]

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.

[siva rama krishnaParticipant]

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

[Damian MarekParticipant]

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

[siva rama krishnaParticipant]

Please reply

[siva rama krishnaParticipant]

Please find the attached paper

Attachments:

1. RZDQPSKmain.pdf

[Damian MarekParticipant]

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

Attachments:

1. HighOrderGaussianPulseCarving.osd

+2

[siva rama krishnaParticipant]

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

[Damian MarekParticipant]

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

[Ibn AzizParticipant]

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:

1. 

   1.jpg
   

[Dr. Dhiman KakatiParticipant]

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

[alistuParticipant]

Please see if my answer in your DQPSK topic helps.

[gaganpreet KaurParticipant]

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

[alistuParticipant]

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:

1. 

   gaussian.jpg
   

+2

[gaganpreet KaurParticipant]

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

[Ashu vermaParticipant]

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.

[alistuParticipant]

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!

[gaganpreet KaurParticipant]

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

[RavilParticipant]

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.

[alistuParticipant]

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.

[gaganpreet KaurParticipant]

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

[alistuParticipant]

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.

[gaganpreet KaurParticipant]

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.

[alistuParticipant]

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.