constellation map after 50km

[boldoo]

dear all,

after 50km optical transmission, how to keep constellation map as possible clear?
For example, 4APSK signals generated by modulator. I can see it by Constellation visualizer. Mr.Damian knows it.

I added 50km fibers and filters. but result is so bad. I tried as 1km fiber, but signal rotated almost -45 degree.

what parameter should be consider in case of 50km? or 80. How to keep clear signal?

if you have some idea, pls kindly share

[Alessandro Festa]

Did you match the reference signal wavelength in the fiber with transmitter and receiver wavelength?

[boldoo]

yes, reference wavelength is 1550nm at TX, RX and fiber and filters. same

[Alessandro Festa]

I remember I had this problem with 100G DP-QPSK but revision 13 solved it. Are you using 13 or 12?

[boldoo]

I’m using revision 13. do you remember which parameters set? and how about components ? amplifier, filter.. is that enough?

[boldoo]

when I deselect “group velocity dispersion” and “third-order dispersion”, constellation map showed almost clear. just attenuated.

do you have idea about to correct the dispersion? need other components?

[boldoo]

Yes, I exactly need Dispersion compensating fiber. DCF. In optisystem, i didn’t find it.

if you know it, please share me

[Damian Marek]

Hi Boldoo,

You can use a regular optical fiber component but manually change the dispersion. As in the attached project.

[boldoo]

thank you dears but it can’t change phase shift. I posted another forum, please review it.

thanks

[Author]

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