Please help me understanding the zero-dispersion wavelength in fibers.

I found this wiki-article on the topic. Accordingly: "In a single-mode optical fiber, the zero-dispersion wavelength is the wavelength or wavelengths at which material dispersion and waveguide dispersion cancel one another."

Does the zero-dispersion wavelength only exist in single mode fibers?

Does it depend on the length of the fiber? Will two single mode fibers with identical step-profile, but different length (5o km and 300 km) have the same zero-dispersion wavelength?

Thanks in advance


1 Answer 1


Dispersion, $D$ is defined as:

\begin{equation} D=\frac{\partial^2k}{\partial \omega^2} \end{equation}

for the whole system, which is length independent (answering second question).

For the first question, then you can see that for highly multimode fibres, waveguinding will not affect propagation much, and the dispersion relation is that of the core's medium. So if it is made of fused silica, then the zero dispersion wavelength will be at approximately $1250\:nm$.

Edit: From what I remember, fibres with big cores just approach the core's propagation, but I might be wrong, after giving it a bit of thought, and multimode fibres might display a stronger dispersion. In any case, the first definition applies, and as you can see its about the dispersion relation of the system.

  • $\begingroup$ thank you for your input $\endgroup$
    – picibucor
    Jun 7, 2021 at 7:34

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