Encyclopedia … combined with a great Buyer's Guide!

Sponsoring this encyclopedia:     and others

Nonlinearities in Fiber Amplifier Modeling

Posted on 2010-03-09 as a part of the Photonics Spotlight (available as e-mail newsletter!)

Permanent link: https://www.rp-photonics.com/spotlight_2010_03_09.html

Author: , RP Photonics Consulting GmbH

Abstract: It is discussed why in the context of modeling of fiber amplifiers and lasers it is normally reasonable to treat nonlinear effects only to a limited extent.

Ref.: The Photonics Spotlight 2010-03-03; encyclopedia articles on nonlinearities, Brillouin scattering, Raman scattering, fiber amplifiers, laser modeling

Dr. Rüdiger Paschotta

I am often asked whether my fiber amplifier and laser modeling software RP Fiber Power can be used for modeling nonlinear effects. Strictly speaking, it can't, as it is not able to calculate the generation of power at new wavelengths through nonlinear effects, including the back-action (depletion) on the original wavelength components. What it can do, however, is to calculate the expected Raman and Brillouin gain. If the nonlinear gain is below the corresponding threshold value, you know that power extraction by these effects is negligible. If not, you know that the calculated powers are actually not realistic, because in reality the nonlinear effects would change the results.

In practice, it is very often fully sufficient to find out whether or not nonlinear effects become important. You do not need to know exactly what would happen in the strongly nonlinear regime, simply because you want to avoid operation in this regime anyway!

One might think that it would be not that difficult to fully take into account nonlinear effects in such a numerical model. After all, the corresponding equations are not necessarily very complicated. This reasoning is not valid, however – for several reasons:

Therefore, in many cases of interest such nonlinear modeling would be extremely difficult, and often at the same time not particularly useful. If anyone claims that his fiber amplifier software can do such things, you should be quite cautions.

Of course, there are cases where the modeling of strong nonlinear conversion processes makes sense. For example, fiber Raman lasers can be modeled with reasonable accuracy, even though it may be difficult to reliable predict the resulting optical spectrum. In the area of fiber amplifiers and lasers, I think it would not make much sense to include nonlinear conversion, and therefore such extensions are not planned for the RP Fiber Power software.

This article is a posting of the Photonics Spotlight, authored by Dr. Rüdiger Paschotta. You may link to this page and cite it, because its location is permanent. See also the RP Photonics Encyclopedia.

Note that you can also receive the articles in the form of a newsletter or with an RSS feed.


If you like this article, share it with your friends and colleagues, e.g. via social media:

How do you rate this article?

Click here to send us your feedback!

Your general impression: don't know poor satisfactory good excellent
Technical quality: don't know poor satisfactory good excellent
Usefulness: don't know poor satisfactory good excellent
Readability: don't know poor satisfactory good excellent

Found any errors? Suggestions for improvements? Do you know a better web page on this topic?

Spam protection: (enter the value of 5 + 8 in this field!)

If you want a response, you may leave your e-mail address in the comments field, or directly send an e-mail.

If you enter any personal data, this implies that you agree with storing it; we will use it only for the purpose of improving our website and possibly giving you a response; see also our declaration of data privacy.

If you like our website, you may also want to get our newsletters!

If you like this article, share it with your friends and colleagues, e.g. via social media: