Germany is funding a research project to develop new types of high-performance mirrors for laser fusion applications. Called SHARP, for Scalable Highpower Reflectors for Petawatts, the three-year project has a budget of €10.4 million ($11.2 million), with €8.4 million coming from the German Federal Ministry of Education and Research. The project seeks to create highly reflective and thermally stable mirror systems that meet the needs of future petawatt laser fusion reactors. To this end, the project will explore large-area and internally cooled high-performance optical mirror systems. A researcher holds a highly reflective mirror for laser applications. Under the SHARP project, the technology will be optimized for laser fusion. Courtesy of Fraunhofer IOF. “These high-performance mirrors represent an indispensable contribution to the realization of commercial laser fusion power plants in reliable continuous operation,” said project coordinator Yakup Gönüllü from SCHOTT. Earlier work on laser mirror systems did not take the thermal aspect of laser radiation into account. In the future, however, the absorption-induced thermal energy input into the mirror systems will be crucial in the continuous operation of laser-driven fusion power plants. Key properties of the high-performance mirrors to be developed in the project are therefore the highest optical quality and a new type of thermal management for the optical components used. In addition to the thermal stability of the new mirrors, the scalability of the technology is also a key factor in the project. Efficient production processes should contribute to the economic and ecological balance and thus to the commercialization of laser fusion power plants. In order to achieve this goal, the SHARP consortium will develop the scientific and technical foundations for novel manufacturing technologies for superpolished, curved, large-area optics as well as methods for removing imperfect substrate areas and so-called “zero-defect” cleaning strategies. For thermal stabilization and active cooling, novel integrated cooling structures in glass substrates and thermomechanical effects are included in the coating development. “The challenge is that the laser mirrors have to withstand extreme loads over a long period of time,” said Nadja Felde, project coordinator at Fraunhofer Institute for Applied Optics and Precision Engineering IOF. “Beyond laser fusion, the targeted developments have great potential for applications in other future markets, especially for high-power laser applications and laser material processing, but also in space communication and especially for the next generation of substrates and coatings for extreme ultraviolet lithography,” said Thomas Höche of the Fraunhofer Institute for Microstructure of Materials and Systems IMWS. The SHARP consortium is coordinated by SCHOTT AG and brings together optics companies and institutes including LAYERTEC GmbH, asphericon GmbH, 3D-Micromac AG, optiX fab GmbH, Cutting Edge Coatings GmbH, robeko GmbH & Co. KG, Laser Zentrum Hannover e.V. as well as Fraunhofer IOF and Fraunhofer IMWS.