Today, we want to introduce Prof. Stefan Nolte. He is a globally recognized expert in laser material processing with ultrashort pulse lasers. A significant accomplishment was the awarding of the German Future Prize in 2013 for the use of ultrashort pulse lasers in industrial mass production.
We are therefore proud to have him on board. The interview was conducted by Ira Winkler.
Spoiler: we also learn something about the history of ultrashort pulse technology.
𝗜𝗿𝗮: Stefan, please introduce the Institute of Applied Physics (IAP)!
𝗦𝘁𝗲𝗳𝗮𝗻: The IAP at Friedrich-Schiller-Universität Jena has been conducting research in optics/photonics and quantum physics for over 𝟯𝟬 𝘆𝗲𝗮𝗿𝘀. With about 𝟭𝟱𝟬 employees, the institute has received numerous scientific awards and published a high number of peer-reviewed journals. The employees also supervise lectures, seminars, internships, and support theses and doctorates.
𝗜𝗿𝗮: What makes the UKP2micron project so exciting for you and what goals are you pursuing with it?
𝗦𝘁𝗲𝗳𝗮𝗻: The research institute aims to expand knowledge and focus on new research topics, such as making the 2 µm wavelength usable for laser material processing❗
We seek to understand the scientific processes at this wavelength and control them technologically for reproducible material processing. The institute partners with companies that offer laser sources, beam shaping optics, and beam deflection systems to support their research. The institute also prioritizes training and incorporates current research results into teaching to develop highly trained researchers and workers for the region's future.
𝗜𝗿𝗮: Why 2 µm? What problems does the 2 µm wavelength solve?
𝗦𝘁𝗲𝗳𝗮𝗻: About 20 years ago, sapphire lasers were used that operated at a wavelength range of 800 nm and were thus able to structure glass in the interior of the volume. Later yberium-based laser systems were then used to write waveguides, cut high-strength glass (mobile phone touchscreens) and even weld glass, as such lasers operate in the 1 µm spectral range.
Driven by the semiconductor industry and the hype surrounding silica photonics, it became increasingly urgent to be able to process silicon as efficiently as glass, i.e. to inscribe conductor paths, cut or join chips. However, only light with a wavelength greater than 1 µm can penetrate silicon, so new laser systems were needed to make the material "transparent". Erbium systems work at 1.5 µm and thullium lasers at 2 µm. This is another very exciting area, as from this wavelength upwards we are working in the absorption range of water.
In summary, the 2 µm technology is capable of handling crucial tasks. It has the potential to significantly enhance the semiconductor industry and can also be utilized in medical fields to process tissue surfaces. However, the 1 µm technology is more suitable for penetrating tissue, which can be advantageous in procedures such as eye operations.
