As head of the Fraunhofer Institute for Applied Optics and Precision Engineering and director of the Institute of Applied Physics at the University of Jena, Prof. Andreas Tünnermann has deep insights into the technology trends in the field of photonics. In our interview, he talks about the fusion of ultrashort pulse and fiber lasers, photonics in Industry 4.0, and the market potentials of quantum imaging and communication.
Prof. Andreas Tünnermann: Human flexibility and creativity will still be in demand in digitally networked, automated production and logistics chains. Photonics is the key so that machines can monitor their surroundings via sensor systems and reliably recognize humans. This is necessary for direct collaboration between humans and machines. This safe, efficient human-machine interaction is the focus of the 3Dsensation innovation alliance in which almost 100 business and science partners from many different industries are involved. Eighty percent of interpersonal communication is visual. We record our surroundings dynamically in 3D and can interpret gestures and facial expressions accurately. We want to transfer these capabilities to machines using optical systems. So that humans and machines can work together and robots become real assistants, we are developing optical sensor systems that analyze human motion sequences in real time and, based on artificial intelligence, make them predictable. This is important not only for production in the future, but also for autonomous driving and to enable people to continue living in their own environment as they grow older. Photonics is the pioneer of digitization: imaging, data processing and communication are conceivable only with the use of photonic technologies.
Tünnermann: USP technology is making rapid progress and achieving power ranges that are interesting for both science and industry. The 2018 Nobel Prize for Physics for Donna Strickland and Gérard Mourou underlines the importance of the technology. Their chirped pulse amplification (CPA) enables generation of very powerful pulses. Actually, our MIMAS project is based on discussions with Gérard Mourou. We are overcoming previous limits of power scaling by parallelizing the pulse amplification. The name of the project, “Multi-dimensional interfero-metric amplification of ultrashort laser pulses,” contains our solution: MIMAS is an active interferometer with laser amplification channels that are merged to form gigantic powers. The pulse peak power and also the average power of the complete system are well beyond the damage threshold of individual amplifiers.
Tünnermann: At present, we already have systems with average power in the multi-kilowatt range. Using frequency conversion methods, we are able to generate extremely shortwave, powerful beams. These secondary sources are interesting sources for imaging and material research, but also for basic research. They are already an alternative to synchrotrons and free-electron lasers. We are convinced that in lithography and metrology, for example, the technology will soon be used in industrial applications. We provide users from science and industry with beamtime through the Fraunhofer Cluster of Excellence Advanced Photon Sources (CAPS). At present there is a lot of demand for a derived coherent source at 13 nm with average powers in the µW range. But scaling of material processing with USP lasers is also attracting interest, where the output powers are in the multi-kilowatt range at 1 µm and 2 µm. Our spin-off AFS – Active Fiber Systems is working with us to translate the technology as quickly as possible into solutions that the market wants.
Tünnermann: In this case, the IOF is cooperating with the Leibniz Institute of Photonic Technology and the University of Jena to develop a new generation of optical fibers that open up special possibilities to control light. We see ourselves as pioneers that enable experiments in basic research and promote innovation. The focus is on active fibers, such as for the generation of ultrashort, high energy pulses in fibers. We are aiming for homogeneous doping and reduced degradation with extreme mode fields and, consequently, low non-linearity. At present, our record is micro-structured fibers with mode field diameters of 200 µm that guide diffraction-limited beams at wavelengths of 1 µm. We are also developing concepts for transport fibers that guide laser beams with very high powers across large distances. This is where the action is at present. Similar to the revolution in laser material processing with a combination of glass fibers and solid-state lasers in the 1990s, in the future, optical fibers will distribute the energy of USP lasers and drive completely new applications. This requires light transmission in which the pulse is not affected by interaction with the fiber. An example of this are hollow-core fibers that guide light in air and thus minimize undesired effects during transmission.
Tünnermann: (chuckles) Our institutes use it intensively and, of course, allow close cooperation partners to use it in some cases. The tower is especially in demand when special requests are made on the precision of the optical fibers. This is because it is seismically and climatically decoupled from the environment. In other words, if you are looking for something special, please get in touch.
Tünnermann: Together with the German Federal Ministry of Education and Research (BMBF) and other partners from science and industry we analyzed where quantum technology would generate added value for our industry. Particularly in the areas of quantum imaging and sensor technology we must make sure that we continue to be a leading sensor country and expand our position. Added value in the use of quantum technologies are foreseeable, because, for example, the wavelength of light for analysis and proof can be optimized separately from each other. Due to its intrinsic, physically contingent high security level, quantum communication also has application potential. It will find a market because it enables data sovereignty inde-pendent of infrastructure. Currently, we are working on a project together with many partners in which we are integrating quantum key distribution in actual communication infrastructures. A light source generates entangled photon pairs that form the basis for crypto keys. If a third party “taps” the light source, the state of the entangled photons changes. The attempt is discovered.
Tünnermann: In Jena, we believe that one of our main roles is to contribute our specific expertise in controlling light to quantum physics experiments in basic research in order to enable third parties to carry out original research and promote applications. Our partners are non-university research facilities, universities and, increasingly, also companies working in the fields of imaging, sensors, communication, and computing that address quantum systems with light. Among other things, we develop special photon sources as well as computer generated holograms, waveguides, glass fibers, and (micro) optics to control light for our partners. Parallel to this, we deal with the issue of the objective evidence of “quantum added value” in actual application scenarios. We can already say that there are opportunities for our medium-sized photonics companies—they could play a leading part in the 2nd quantum revolution.