New Paper on Power Scaling of Lasers

Posted on 2007-12-03 as a part of the Photonics Spotlight.

Permanent link: http://www.rp-photonics.com/spotlight_2007_12_03.html

Author: Dr. Rüdiger Paschotta, RP Photonics Consulting GmbH

Ref.: “Power scalability as a precise concept for the evaluation of laser architectures” in arXiv.org, see arXiv:0711.3987v1; encyclopedia article on power scaling of lasers

This week I published the above mentioned paper in the open-access repository arXiv.org. It is truly amazing that even though the term “power scaling” has been used for decades in the area of laser technology, this paper is the first (apart from my encyclopedia article) to give a solid definition of power scaling and scalability. (Anybody not believing this is kindly asked to provide me with a reference proving the opposite.) The motivation of that work is not only that it is very advisable to use clearly defined terms (rather than vague or even meaningless buzzwords) in science and technology, but also that serious thinking with that concept in mind can inspire a lot of useful thoughts, as common issues of high power lasers appear in a new light. In other areas of technology, such as computing, data storage, communications, and manufacturing, that lesson has been learned much earlier than in laser technology.

In very brief terms:

• I recommend not to use the term “power scaling” just for some measure to squeeze somewhat more power out of a laser (even though sadly this has become very common). True scaling is more specific: it is the application of a systematic, well-defined and repeatable scaling procedure to turn one working laser design into another one with higher output power – without using additional inventions and without making any of the main challenges more severe. Precise and practical criteria for power scaling are given in the paper.
• The idea is certainly not to dismiss anything which is not true scaling. In some sense, even the opposite may be supported: the pure application of a systematic procedure, avoiding inventive steps, is not what we call creative work. However, it can be very creative and productive to recognize or arrange a situation where true scaling is possible.

There are, of course, plenty of reasons to hate this paper:

• Those who abused the term “power scaling” in the past, and those who used the term “scalable laser architecture” for their favorite type of laser, may not like to be told that this was and is not appropriate.
• It may be hard to get rid of the feeling that “scalability” is a kind of quality label which has to be defended for a particular laser under any circumstances.
• Even those who have nothing to lose may resist changes in thinking. Sadly, this is common even in science.

Anyway, I hope the paper will be useful for many. An aspect which should help is the open-access nature of the arXiv repository.