Dispersion Shifted Fiber

[Sasha]

Hi all,
I am working on optifiber tutorial. Link is here.

Dispersion Shifted Fiber

In Dispersion Shifted Fiber, when changing the zero dispersion wavelength, how to identify the dispersion value of 3ps/nmkm has to be moved and then changing the fiber profile, how to know that region1 is to be changed and then region1 width value to 1.32m?

Thanks in advance.

[Sasha]

Hi all,

how to design DCF fiber in optifiber? any example please

Thanks in advance.

[Steve Dods]

In the original design, Region 1 had a width of 0.6 µm. With this design, the dispersion at wavelength 1.55 µm is 3.06 ps/km nm. The target is a design with zero dispersion at 1.55 µm, or about 3 ps/km nm lower than this. In the next simulation, done at wavelength 1.3 µm, the width of Region 1 is scanned. In that simulation, the original design, which has Region 1 width of 0.6, has a dispersion of -20.34 ps/km nm. From the width scan, we see that when that width is changed to 1.3, the dispersion goes to -23.2 ps/km nm (a reduction of about 3 ps/km nm). This suggests that changing the width from 0.6 to 1.3 might get close the target design for the wavelength 1.55 µm. Applying some interpolation gets the more precise width of 1.32 µm.

[Sasha]

Thanks a lot Steve. Can you give some suggestion about designing DCF?

Thanks in advance.

[Sasha]

One more question, in the previous example we have a 4 regions but how to do we know that region 1 has to be changed?

Thanks in advance.

[Steve Dods]

Probably the desired effect can be achieved by changing almost any of the regions. The choice of Region 1 is partly convenience (it would not be difficult in fabrication to change the width of that region), and partly function. The outer ring (Region 2) affects dispersion according to its exposure to the modal field. That field is exponentially decreasing in the first cladding (Region 1), and so it is expected the dispersion should be sensitive to the width of Region 1. Maybe that is why the width of Region 1 was selected for modification.

[gaganpreet Kaur]

to design a dispersion shifted fiber u need to fix dispersion and reference wavelength. then u fix get the second order dispersion paarmeter beta2. from the formula of dispersion slope for given value of beta3 that is third order dispersion parameter u calculate the dispersion slope or vice a versa. the related theory is given in book on Fiber optical comm by G.P. Agrawal in the first chapter itself

[gaganpreet Kaur]

i would like to add i mentioned it is another post too for given SMF transmission fiber DCF is calculated by using relationship
L1D1+L2D2=0 where L1 , D1 refer to length of SMF and D1 is its dispersion at reference wavelength. while L2 is length of DCF needed and D2 is dispersion needed at same reference wavelengt

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