RP Photonics logo
RP Photonics
Technical consulting services on lasers, nonlinear optics, fiber optics etc.
Profit from the knowledge and experience of a top expert!
Powerful simulation and design software.
Make computer models in order to get a comprehensive understanding of your devices!
Success comes from understanding – be it in science or in industrial development.
The famous Encyclopedia of Laser Physics and Technology – available online for free!
The ideal place for finding suppliers for many photonics products.
Advertisers: Make sure to have your products displayed here!
… combined with a great Buyer's Guide!
VLib part of the

The Photonics Spotlight

The Ideal Pump Intensity Distribution in an End-Pumped Solid-State Laser

Dr. Rüdiger Paschotta

Ref.: encyclopedia articles on end pumping, side pumping, thermal lensing, beam quality, resonator modes, mode coupling, and alignment sensitivity; R. Paschotta, “Beam quality deterioration of lasers caused by intracavity beam distortions”, Opt. Express 14 (13), 6069 (2006)

In the scientific and technical literature, one often comes across the question what shape and size of pump intensity profile is ideal for an end-pumped laser. The given answers vary quite substantially and sometimes even appear to be in outright contradiction with each other. I suppose that many people would like to know what the right answer is.

Here it is: it depends! I am sorry, but that's true, even if we consider only lasers with diffraction-limited (TEM00) output:

In this context, it can be important to understand how exactly aberrations influence the laser's beam quality: via mode coupling – see the paper cited above. Interestingly, this crucially depends not only on mode sizes in the laser crystal, but also on other properties of the resonator design.

So we see that a universal answer cannot be appropriate. To find out what is best in a concrete case will often require either a carefully worked out approach, based on the detailed understanding of the relevant physical issues, or an experimental trial-and-error approach which might be tedious and result in non-ideal performance or stability. There are, however, cases e.g. where only a low output power is required, and the design is not critical.

In any case, however, it is highly recommended to carefully check the pump intensity profile e.g. with a beam profiler even before building the laser resonator. By trying to save a little time at this point one may later on get into trouble e.g. with instabilities, and it takes much longer then to identify and cure the cause.

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

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: