What is the role of femtosecond laser systems in the research of nanomaterials? We are talking to Pieter Geiregat, Associate Professor at Ghent University, about his field of research. He chose Laser 2000 as the supplier of a Light Conversion laser system that plays a central role in his research. What is he specifically studying, and how will we see the results of his research in practical applications?

Pieter Geiregat, Associate Professor at Ghent University, is studying nanomaterials, which are materials structured on the scale of 1-100 nanometers (nm = 10-9m) with semiconductor properties for applications in optoelectronics and light-driven chemistry. He focuses particularly on the interaction of specific materials with ultrashort laser pulses. His group works on understanding the fundamental processes related to the absorption and emission of light, which semiconductors excel at, leading to insights that are useful for the development of the next generation of light sources (LEDs, lasers) or photodetectors (such as hyperspectral cameras for smartphones). He chose Laser 2000 as the supplier of Light Conversion femtosecond lasers, which are instrumental in this research. We spoke with him about his research and the collaboration with Laser 2000.

Interdisciplinary Research in Physics and Chemistry

Geiregat started studying applied physics and quickly realized that his interest lay in research at the interface of chemistry and physics. Specifically, he focuses on using cheap and versatile solvent-based chemistry to create new materials from atomic building blocks and then studying the physical properties of these materials. The goal is to discover materials that unlock new possibilities in light-matter interaction. His research work has two directions:

"My recent ERC Starting Grant [research on 'mid-infrared emitting nanomaterials'] focuses on fundamental research. The question there is 'Can this work, and what are the consequences of certain modifications we make to the composition or structure of the nanomaterial?' Those are very open, academically-oriented research questions. We call it 'blue sky research.' It's often the most exciting for researchers because it can uncover entirely new things. But it's also very uncertain and sometimes difficult to secure funding.

At the same time, there is a lot of emphasis in Flanders on what is called strategic basic research. In this case, you work together with companies to explore certain properties of materials. For example, you steer your research towards a demonstrator that achieves a certain cost, efficiency, or form factor. The company says, 'To be commercially viable, we need to improve this by a factor of 10.' Then we specifically search within that material or technology for possibilities to achieve that goal."

Femtosecond Lasers

For his research, Geiregat has access to a setup of various femtosecond lasers. These ultrafast lasers can generate femtosecond pulses and form the basis of his research on the properties of (new) materials.

"With these lasers, you can perform time-resolved experiments. You try to understand the dynamics of materials when you disturb their equilibrium, for example, by absorbing light. For almost all materials, this dynamics occurs on incredibly fast timescales, on the order of picoseconds or nanoseconds. Therefore, we also have to work on these ultrafast timescales. A small modification in our materials, such as the shape, composition, or size, can have a significant impact on such a short timescale, but you need to be able to observe it. These lasers make that possible."

Eureka!

For many people, this kind of research is quite abstract. Therefore, we asked Geiregat about a real 'eureka!' moment when his research yields concrete results.

"A great example is the search for a cheap and easy-to-process material capable of amplifying light. A laser distinguishes itself from an LED because the active semiconductor material can also amplify light, not just emit it, resulting in bright, directional light with high color purity. This light amplification effect has been known in our world of nanomaterials for 20 years, but no nanomaterial has demonstrated all the desired properties and thus become competitive with existing materials. The advantages of lower cost and processability of nanomaterials have not outweighed their drawbacks. Last year, we finally found a material that meets all the requirements. With this material, we can now look to the future and make a difference in people's daily lives.

For me, it's a 'eureka' moment when I realize that the application will actually materialize after years of fundamental research. When we transition from a broad research vision to real focus and start working towards practical applications. I chose to study applied physics for a reason, and I derive a lot of energy from the application of my research."

Light Conversion Laser System

The femtosecond laser system is instrumental in this research, and the right setup can make a big difference. Geiregat chose a laser system from Light Conversion, for which Laser 2000 has the exclusive distribution rights in the Benelux region:

"I worked with Light Conversion lasers during my doctoral research and post-doc, so we already had a preference when we received funding for this research. But while we spent a lot of time adjusting the titanium-sapphire systems, this new system is so stable that we can focus much more on the science. Light Conversion has truly made a push into the academic context, not only by shortening the pulse duration but also by improving reliability and stability, which is crucial. Sometimes, my team is amazed and says, 'Remember how much time we used to spend on...' It's much more stable now, almost like an industrial setting; the setup can be active almost 24/7. And by choosing Light Conversion, we could get everything from one supplier, which is a huge advantage in terms of both support and compatibility."

Collaboration with Laser 2000

Geiregat has worked with Laser 2000 and specifically with our photonics specialist, Davey Loos, to his full satisfaction.

"When a government institution makes such a large purchase, there is a whole tendering process involved. It helps to be able to communicate transparently about prices, expectations, and possibilities. And that has always worked very well with Laser 2000, especially with Davey. As an academic institution, we make such a large purchase only once, and that puts some pressure on us. We expect certain performance and support, and Laser 2000 was simply a good choice. I think Laser 2000 is a good representative of Light Conversion.

Therefore, it was logical that when we expand or rebuild the setup, we collaborate again with Davey and Laser 2000 to achieve an optimal result. They are very involved in the process, considering what is possible or not, and come up with good suggestions. We know how lasers work and how to use them, but we rely on them for the technical details and the possibilities. It all runs smoothly."

Davey Loos, photonics specialist at Laser 2000 and Geiregat's contact person, adds:

"Ultimately, you want to work together with three partners—Ghent University, Laser 2000, and Light Conversion—to achieve an optimal setup. The involvement that Laser 2000 has with Light Conversion makes it very easy to do that. Behind the scenes, things that Pieter often doesn't even see, we have daily contact and exchange information and knowledge. And ultimately, a distilled concept goes to the customer

that is workable. We bridge the gap, helping Light Conversion understand what Pieter wants to accomplish and providing the right solution."

Future Applications of Nanostructured Materials

Finally, we were curious about the applications of the nanostructured materials that Geiregat is studying. When will we encounter them in everyday life?

"A great example of an application that stems from this research field is QLED TVs. These are essentially blue LEDs coated with nanomaterials that absorb that blue light and convert it into green and red light with very high color purity. These 'quantum' materials can be used as a kind of color wheel, creating specific colors by adjusting the properties, such as size, of the material on the nanoscale (1-10 nm).

In the shorter term, the most interesting applications are in the visible spectrum. [Infrared applications are further down the line.] I'm mainly thinking about making laser-based technologies more accessible. What we see today in many consumer products, such as smartphones, are light-emitting diodes. It's a process with relatively low light that radiates in all directions. What we're moving towards is laser technology that can emit very directional, monochromatic, and bright light, for example.

Looking further ahead, you can consider the concept of LIDAR. The goal is to develop cost-effective sources and detectors for both emission and detection, enabling the realization of self-driving cars. But you can also think of miniaturized sensors that relieve the semiconductor industry of the high cost of expensive crystal growth processes, using printable materials.

Essentially, we are trying to bring cheap, printable semiconductor technology to the market. And the timing is perfect. During COVID, we all realized how important the semiconductor industry is, which led to the European Chips Act. Printable semiconductors would be a crucial building block for a more independent European chip market. We could start producing more semiconductors and optical materials ourselves, reducing dependence on other regions. Our research is fundamental to taking that step."

Are you also curious about the Light Conversion program or do you have a specific question about the application of lasers in your field of research? Contact Davey Loos at davey@laser2000.nl or +3211757987.