[Abdallah IsmailParticipant]

I’m not sure.
If you are working on back to back system, you may not need to DSP. Otherwise, the DSP may be important as the fiber length increase.

[Abdallah IsmailParticipant]

It is a very important part in your system.
Also at first remove all impairments like noise from the system.

[Abdallah IsmailParticipant]

Sure

[Abdallah IsmailParticipant]

I think that I faced that problem with PM-QPSK. check Polarization De-Multiplexing using DSP.
BER is zero because all the samples are in the right corners.

[Abdallah IsmailParticipant]

Sure, It is very nice to increase the constellation level to increase the data rate or the transmission rate. However, as you are increasing the constellation level, you will use much power and hence the non-linearity will appear in long haul.
DP-QPSK is the most common used one.
DQPSK is used to ease the detection without LO.

[Abdallah IsmailParticipant]

The eye diagram is two pulses plotted one up and one down inverted. To appear like the eye.
So it is a unit of pulse amplitude.

[Abdallah IsmailParticipant]

You can find Matlab file for DSP. It contains CMA algorithm for QPSK. It is easy to develop it to QAM.
100 Gbps DP-QPSK

OptiSystem – Hot Topics

By the way CMA is not for Dispersion compensation as my knowledge.

[Abdallah IsmailParticipant]

It is simply digital to analog converter.

[Abdallah IsmailParticipant]

I think Q = sqrt (SNR). So Q^2 is a proportional to SNR and can be measured in dB. However, you can measure any value in dB, it is a log scale even if it is a unitless like SNR (Unitless).
If you are using eye diagram, the Q factor is estimated from the Eye opening. So, it may take very large values in case the Eye is well opened.

[Abdallah IsmailParticipant]

you can attach your file and I’ll check it tomorrow.

[Abdallah IsmailParticipant]

There is a BER test set that generate a stream of data and receive it where it compares the generated with the received.
In case of using DSP to compensate the dispersion, Eye diagram will not give you reasonable results.

[Abdallah IsmailParticipant]

You get a perfect comb. You can decrease the line width of the laser to show a clean image. However your results is perfect.

[Abdallah IsmailParticipant]

to my knowledge, There is no device for pulse picker in Optisystem.
you can use MZM for that purpose.
check the attached paper.

Attachments:

1. oe-17-8-6584.pdf

[Abdallah IsmailParticipant]

Sorry aadilqau,
I use the last version. However, you can use the attached snapshots to design in your own software.
I hope this help you.

Attachments:

1. 

   flat01.png
   

2. 

   flat02.png
   

[Abdallah IsmailParticipant]

This is a general concept.
optical signal in the optical domain while the binary signal in the electrical domain.
At least, you need a photodiode with an amplifier.