Residual Dispersion (ps/nm)

[Muhammad Mansoor Ashraf]

I am working on a system consist of SSMF and DCF. I want some results using reidual dispersion (ps/nm).
How can I introduce residual dispersion parameter (ps/nm) in fiber.
Kindly guide me.
I have to plot residual dispersion vs OSNR.
Thanks in advance.

[Alessandro Festa]

Residual dispersion depends on the amount of DCF you put into the fiber. Supposing fiber is 17 ps/nmkm and its length is Lf; and DCF is -100ps/nmkm and length is Ldcf, the residual dispersion is Lf*17-100*Ldcf.

[Ravil]

Hi Muhammad,

I agree with Alessandro’s explanation, just want to add a little more elaboration here. SSMF and DCF are characterized by the dispersion coefficients: 17-18 ps/nm*km and -80-100 ps/nm*km respectively. Without taking into account polarization modal dispersion effects, your residual dispersion can be determined using the provided above equation. This dispersion in its turn will determine the Bit Error Ratio (BER) for you system. From BER you’ll be able to calculate OSNR.

[Alessandro Festa]

One more thing. Residual Dispersion vs OSNR curve also depends on the nonlinear impairments in the system, so the curve changes if you change launch power into the fiber!

[Alessandro Festa]

Hi Muhammad, were you able to plot the curves?

[Ravil]

Hi Muhammad,

Alessandro brought a very important point to this discussion! You will have a dependence on nonlinearities in your case. It should be clearly seen when you very the length of DCF.

[Muhammad Mansoor Ashraf]

Yes, I have plotted the curve, thank u Ravil and Alessandro! I have considered the nonlinearities also.

[Ravil]

You are welcome Muhammad! I am glad that my advice helped you! Best of luck with your work and research!

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