Laser Technology: The Power of High-Power Lasers

September 14, 2026

Laser technology has long been part of our everyday lives: We scan our groceries at the supermarket checkout, data is transmitted in the form of light signals, and lasers have been used in medicine for many years. But that’s just the beginning—the possibilities for the future go far beyond that.
Today, high-power lasers are being developed and used in research. This brings together various fields of research, and the insights gained from them, in turn, give rise to entirely new areas of application.
What can high-power lasers actually do, and what potential do they hold? Dr. Tanja Jovanovic discusses these and other questions with Prof. Dr. Jörg Schreiber, group leader for laser-ion acceleration, and Prof. Dr. Stefan Karsch, group leader for high-power laser development, electron acceleration, and applications at the Center for Advanced Laser Applications (CALA).

This shows the potential your research holds for the future of medicine. What major milestones have you achieved at CALA so far?

Prof. Dr. Stefan Karsch: First of all, we were able to build the laser system in a relatively short amount of time. When I compare it to similar lasers—of which there aren’t many worldwide—ours is the most powerful laser system in Germany and ranks among the most powerful globally. And we built it in record time and within budget. So it all came together relatively quickly.

How long did it take you to do that?

Prof. Dr. Stefan Karsch: About three years from the start of construction to commissioning. It took another one to two years before we started getting really good results. A comparable large-scale project at the European level is ELI, for example. Work there began a few years earlier, but they didn’t reach the same level of performance until five years later. We’re proud of that.
This is also because we had already operated several such lasers before—not exactly with these parameters, but we’d been familiar with the field for quite some time. We are now able to generate high-quality particle beams that, under certain parameters, are actually world-leading. With electrons, for example, we can generate beams with a previously unknown charge—that is, a very high number of particles per particle packet—and a sharpness that has never been achieved before.
Now the goal is to keep improving the facility, taking small steps along the way. After all, research is always a series of small steps. And at some point, one of those steps leads to a major new idea, which we then pursue further. We’ve had a few of those recently, and they’ve gone well.

What makes your research infrastructure at CALA so special? Why are places needed where laser development, experiments, and—above all—application prospects come together?

Prof. Dr. Stefan Karsch: Lasers of this magnitude are typically housed at national institutes. These are user facilities, which means I have to submit a proposal if I want to conduct research there. The proposal is reviewed, and then I’m allowed to conduct experiments under very controlled conditions to ensure nothing happens to the facility. At CALA, we have the advantage of owning such a facility ourselves—one of the same scale, or in some cases even larger. We can do whatever we want with it, and thankfully, we also know what we can do with it. This helps us pursue new ideas much more quickly. And that’s incredibly valuable.
Another aspect that’s naturally important to us—and which can be both an advantage and a disadvantage for our staff—primarily concerns the doctoral students we supervise. They must work on both the laser and the experiment and become familiar with both so they can determine the optimal laser parameters for their experiment. As a result, it takes them longer to collect their data. In return, however, they achieve a level of quality that would be very difficult to attain if they only had a few weeks of beamtime once a year at a user facility.
Here, these experiments can run for extended periods and be continuously optimized. This naturally helps us remain competitive, despite our relatively small group size and modest financial resources—especially when compared to a large-scale laboratory. And that’s quite a luxury—we’re very, very happy that the Bavarian state makes this possible for us. But of course, it’s also a burden, and we have to make sure we live up to that responsibility.

Prof. Dr. Jörg Schreiber: Of course, we also have the advantage that we have a large community of researchers at LMU, which brings together diverse areas of expertise. I’m part of Prof. Dr. Katia Parodi’s Department of Medical Physics, while Mr. Karsch is part of Ferenc Krausz’s Department of Laser Physics, and this interdisciplinary approach naturally drives innovation as well.
We have many different ideas for applications. At the same time, being able to conduct research in all directions helps us stay on track. The fact that medical applications are always at the center of our work is a key point here. But as Mr. Karsch already noted, we’re also flexible. When opportunities arise, we can enter into collaborations if they make sense for both sides and open up new fields of research.

So this freedom also allows you to pursue new research directions early on. We’ve already discussed that you’re also conducting research on laser fusion. How did that come about?

Prof. Dr. Jörg Schreiber: That’s a great question because it gives me a chance to talk a bit about the history. Very few people know that the research we and our colleagues around the world are engaged in today actually arose from an accident. In the 1990s, research on laser fusion revealed that high intensities are actually detrimental to fusion.
At that time, the Max Planck Institute for Quantum Optics in Garching was spun off from the IPP, the Max Planck Institute for Fusion Research, to make more room for laser fusion. Based on that research—Mr. Karsch was there from the start, and I joined relatively soon after—we then moved into our current line of work: building laser particle accelerators. That’s why I find it very interesting that new ideas are now emerging to use short-pulse and high-intensity lasers for fusion again, using new approaches. This brings us back to our roots. It didn’t just happen by chance. Back then, we were approached directly by Marvel Fusion, one of the laser fusion startups in Germany, asking if we’d like to collaborate. There are many fundamental physics questions where we can work together very well. We saw the potential and the opportunity and dove right in.

Prof. Dr. Stefan Karsch: Of course, we’re not the leading fusion researchers—that much must be said. But there’s significant overlap with our research. In particle acceleration, we aim to achieve very high energies with a relatively large number of particles and very well-focused beams. Marvel Fusion, on the other hand—to put it simply—wants a “hammer”: many more particles with less energy.
The fundamental questions, however, are very similar: How do I couple laser energy into plasma as efficiently as possible to accelerate particles? We see great synergies there. That’s why I believe it’s a win-win situation for both sides, partly because both have a stake in the laser’s further development. That’s why we’ve thrown ourselves into this new field with joy and enthusiasm. Although we can’t really evaluate the concept that Marvel is pursuing.

There are many so-called spillover effects in your research. What new methods, technologies, or insights have emerged most recently?

Prof. Dr. Stefan Karsch: The classic example—though I wouldn’t really call it a spillover effect—is particle acceleration. Particle accelerators are found everywhere in research: from X-ray tubes to the large accelerator at CERN, all the way to free-electron lasers (FELs) or synchrotrons, which are used, for example, in biological research, the life sciences, or materials research. We believe that with these lasers, we can generate extremely high acceleration fields and, in a very short time, produce beams from very small spatial regions that are significantly denser and more focused than those from conventional machines. There are also drawbacks, which is why we cannot yet replace conventional systems. But that’s not what we’re working on anyway.
Rather, we want to tap into new niches for these accelerators where their particular strengths come into play: extremely short particle pulses, which we can use to investigate highly dynamic processes; the conversion into secondary radiation such as X-rays; or the focusing of ions onto the smallest possible areas. These are things that aren’t really possible with the machines we’ve had so far.
Prof. Dr. Jörg Schreiber: I’d perhaps mention one more potential spillover effect that we haven’t observed yet, but hopefully will. The electrons that Mr. Karsch provides to generate these brilliant X-rays—and thus images of tumors—can also be used, for example, to look inside fusion plasmas. This is one of the synergies that is currently developing. It’s not market-ready yet, but if you ask me, it’s coming.

Prof. Dr. Stefan Karsch: A typical feature of laser fusion is that I have to strongly compress a fuel pellet—or whatever form the fuel takes. The degree of compression varies depending on the application. Then I have a high-density plasma, and the whole thing lasts only about one picosecond. The entire fusion process must take place within that time.
How do I compress this matter so quickly and to such a small size—and still be able to observe it? That’s exactly what a few femtosecond pulses make possible. I’m talking about some strange numbers here: What is a picosecond? What is a femtosecond? A picosecond is one trillionth of a second, and a femtosecond is one quadrillionth of a second. We’re operating on these unimaginably short timescales.

Are there any research milestones at CALA that you’re particularly looking forward to in the coming years?

Prof. Dr. Jörg Schreiber: I used to celebrate whenever we managed ten laser pulses a day. These intense lasers each generate only a single short pulse. Today, we can generate one laser pulse per second and thus accelerate ions once per second. So we can turn on the machine and let it run for half an hour or even longer. Ions are emitted once per second.
For me, the next milestone would be to use this to demonstrate the first truly effective applications. That could be, for example, the irradiation of tumor cells, which we observe in real time while we’re irradiating them. That hasn’t been possible at all until now. Because we accelerate the ion beams with the laser, we can simultaneously observe what’s happening at exactly the right moment. So far, we’re doing this first in water, and later in cells. This allows us to investigate, at the physical and chemical levels, which processes are triggered by the protons or ions. For me, that would be a milestone for the coming years: to measure, on a time-resolved basis, which processes occur until the cell eventually dies.

Prof. Dr. Stefan Karsch: From my perspective, of course, I also have a “Holy Grail”—or even two. One Holy Grail in electron acceleration is achieving beam quality so high that it can be used to operate a free-electron laser. In Hamburg, for example, there’s the European Free-Electron Laser. It’s three kilometers long, costs, I believe, 10 or 15 billion euros, and is a flagship for large-scale experimental campaigns.
We’re trying to shrink this accelerator down to a few centimeters. If we succeed and the beam quality becomes good enough, we could also use it to operate a free-electron laser. A few years ago, we discovered a trick that, through a two-step process, actually gives us a realistic chance of achieving this. The laser accelerator community has been pursuing this goal for 20 years. So far, we’ve only scratched the surface, but we hope that with our approach, we can truly enter this regime. To that end, we’re currently finalizing a proposal that has a relatively good chance of receiving funding.
The other goal concerns our laser, which currently fires once per second. Mr. Schreiber previously said “only” once per second, and that’s exactly right, because a conventional source can do this a thousand or even a million times per second. We are therefore developing concepts using another laser, which is also located here, that will allow us to accelerate electrons a thousand times per second and thereby generate X-rays again. This would result in a significantly higher average power. If I then wanted to examine someone, that person wouldn’t have to wait ten minutes, but only a few seconds. That would be a major breakthrough, and we hope we can achieve it.

If you could wish for three things to bring your research to practical application more quickly and advance the technological landscape, what would they be?

Prof. Dr. Jörg Schreiber: Let me start with the most important one: I believe it’s laser technology. But Mr. Karsch is the expert there. All I know is that we really need to improve in that area.

Prof. Dr. Stefan Karsch: What’s actually a major problem, especially in Germany, is this: We have world-leading laser manufacturers who are very good. What they’re particularly good at are lasers for industry with very high average power but very low peak power. That’s exactly the opposite of what we need. We need very high peak power and, at the same time, high average power. That’s why we currently have to purchase such lasers from other countries.
We need significantly more support from industry here. As long as we’re conducting research on accelerators in academia and they aren’t yet in practical use, the incentive for industry to get heavily involved is, of course, low. That’s why we’re also pinning our hopes on fusion startups, which can provide another boost.
Hopefully, German industry will then be able to make decisive progress with these lasers—both in terms of the required materials and in terms of mirrors with a high damage threshold and the pump units. These are diodes that are currently still very expensive. If we make progress here, we’ll be able to continue upgrading our lasers in the future and keep pace with developments. That’s an important point.

Prof. Dr. Jörg Schreiber: Of course, the staffing situation is also important. We simply need good young scientists. As a university, we can certainly work on that.

So, more doctoral funding for research?

Prof. Dr. Jörg Schreiber: I think that always helps. I feel like we’re sitting here a bit in an ivory tower and are incredibly lucky with our people. But I think what you said hits the nail on the head: We have to consistently promote the idea that research is simply cool. It’s wonderful to unlock nature’s secrets. And if you can then apply that knowledge to something practical, that’s wonderful, of course. But the practical application shouldn’t necessarily be the main focus.

Prof. Dr. Stefan Karsch: That depends. Of course, we need people who can translate this into practical applications. That’s not our role—otherwise, we wouldn’t be at the university. We’re actually basic researchers. That’s very important, because without basic research, applied research is pretty much lost. We have to start somewhere, and we’re right at the beginning. Thankfully, we also have many young researchers who are looking more toward practical applications and are also heading toward startups. That’s important. I believe we simply need to integrate all of this better.
Of course, private investors also play a role here. That doesn’t work as well here yet as it does in the U.S. I believe this spirit needs to come to the fore more strongly here, too, because we’re not that bad. We’re capable of achieving things in Germany.

The interview was conducted by Dr. Tanja Jovanovic, Head of Marketing & Innovation and Member of the Executive Board, Bayern Innovativ GmbH, Nuremberg.