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RP Fiber Power – Simulation and Design Software for Fiber Optics, Amplifiers and Fiber Lasers

Frequently Asked Questions

Scope of Application

Is this software a tool for experts or rather for beginners?

Through a clever combination of simple interactive forms with a powerful script language, RP Photonics has managed to create a tool which serves very well both beginners and experts. You will quickly get your first results, but even in complicated situations you will not quickly hit limits as it is often the case with other products.

Can I model cladding-pumped devices?

Sure, you can. In most cases, you just define a pump channel, having an intensity distribution which is flat over the whole pump cladding and the core. If the pump cladding is circularly symmetric and does not have more than a few hundred modes, you can even simulate the evolution of all pump cladding modes separately. And for any shape and size of pump cladding you can numerically simulate the beam propagation.

How about new laser transitions?

No problem. You can define any energy level scheme of some laser-active ions, and all kinds of processes leading to transitions between those. Even different kinds of ions in a fiber can be included. A challenge may be to obtain the required spectroscopic data (transition cross-sections etc.). Maybe you will be the first to measure them. And the software can help you to extract such spectroscopic data from your raw data, and also to plan your measurement campaign.

Can I use RP Fiber Power also for bulk lasers?

Yes, you can, provided that the shape of the transverse intensity profile in the laser crystal can be assumed to stay approximately constant. This assumption is very reasonable for many bulk lasers, particularly to those operating on a single transverse mode, but also others operating on many transverse modes.

Can I simulate effects of bending a fiber?

The integrated mode solver cannot calculate the modes of bent fibers. However, you may import the modes calculated by some other software. If you know the mode-dependent bend losses, you can use these data in the software.

Since V5, RP Fiber Power can do numerical beam propagation, and here you can have arbitrary bends – even with arbitrary evolution of bend radius along the fiber.

Can RP Fiber Power take into account fiber nonlinearities?

Nonlinearities are most important for ultrashort pulse propagation. In such simulations, you can investigate not only the Kerr effect, leading to self-phase modulation, but also consider a delayed nonlinear response, which leads to stimulated Raman scattering. However, the interaction of multiple optical channels via optical nonlinearities can not be simulated.

Dynamic simulations can involve the interaction of many optical channels, but here the effects of nonlinearities can not be modeled. However, in most cases it is possible at least to check whether fiber nonlinearities would have a substantial effect on the results. For example, you can let RP Fiber Power check whether or not you will be above the threshold for strong stimulated Raman scattering. Only, the software can not calculate what would happen in the regime of strong nonlinear effects. This means that you cannot use it for modeling Raman fiber lasers, for example.

It might be that a future version of RP Fiber Power will be able to take into account stimulated Raman scattering also in dynamic and steady-state calculations.

Can I get a special version with extended features?

If you suggest an extension of RP Fiber Power, which the developer judges to be useful for many users and not too difficult to make, this can often be done. You may be the first getting this improved version – without extra cost.

If you need a very special extension, which is of interest only for you, just ask RP Photonics. It may be possible to do that extension, using some of your support time or an extra payment.


How do I know whether the results are calculated correctly?

This is an important question. Absolutely error-free software of non-trivial kind is impossible to make, and it can be worse than a nightmare to be served with wrong results without noticing that. However, RP Photonics offers you a particularly high degree of confidence:

  • First of all, the developer (Dr. Paschotta) is widely known as a distinguished expert in this field, who understands very well the involved physics and has many years of experience with advanced computer modeling.
  • Dr. Paschotta is aware of different ways in which errors can occur, and knows how to encounter all these possibilities – you can see that from his Spotlight article of 2008-11-08. He has devoted substantial efforts to ensure the correctness of the code.
  • The script language of RP Fiber Power makes it fairly easy to do certain sanity checks.
  • If a user has any reason to suspect an error in the software, Dr. Paschotta will carefully check that. If an error is found indeed, it will be fixed quickly. In the case of a serious bug, existing customers are notified and offered an updated version (without payment).
  • In cases where you are not sure about the applicability of the model, or the right way of implementing a model, Dr. Paschotta will help you as part of the technical support.


Can I import and export numerical data?

RP Fiber Power can import numerical data from comma-separated (.csv) files, for example, and also export any data in that form. For special file formats (e.g., binary ones), RP Photonics may offer a custom extension.

Most users need such import/export only rarely, since the software is so powerful that you normally do not need other software for processing input data, for example, or for graphically displaying results.

Can I systematically vary certain parameters in the model?

Sure; due to its powerful script language, RP Fiber Power gives you extreme flexibility for such things. For example, you may run through multi-dimensional parameters spaces with given step sizes or with random values, for example for a Monte-Carlo simulation.

Licenses and Support

(Please note that in case of doubt the license contract and not this text defines what is legally binding.)

What exactly determines whether I can use non-commercial user licenses?

The crucial criterion is whether the software is used for commercial purposes:

  • For a university or research institute, non-commercial licenses are usually sufficient. You can use them for research and eduction. However, if the software is used in a cooperation with a company, then at least one of the involved parties must have at least one commercial license.
  • For companies, a commercial use is basically always assumed; even if the software is initially used only for feasibility studies, for example, ultimately a company is pursuing commercial goals.

Is the user license valid for one year or indefinitely?

Normally, a user license is valid indefinitely. Only in special cases, RP Photonics has agreed to sell a time-limited license.

Are there discounts for multiple licenses?

Yes. Once you have one license, further licenses for use within the same company or institute are available at a substantially reduced price.

For how long will I get technical support?

The current license contracts state that some number of support hours included in the license fee can be used within 4 years from the software delivery. That does not mean that there will be no support thereafter; RP Photonics is expected to exist for many years to come and also to sell such software licenses for a long time.

Will I have to pay for updates or upgrades?

Normally, updates are available for free. However, if a new version of the software appears, which has substantially extended features and is sold at a higher price, upgrades to that new version are not free. Existing customers then obtain an upgrade offer, the price of which will not be substantially higher than the difference of license prices.

When I need to move to a different PC, can I move the license to it?

Normally you can. The license contract gives you the right to get a new activation if you can prove that you deactivated the old ones, or that the PC went out of service. (Please ask RP Photonics how to deactivate the license before you remove the software from the original PC.) If you cannot prove it – for example, if your PC went defect – it is to the discretion of RP Photonics whether you get a new activation. So far, there has been no case where RP Photonics rejected this.