The race toward high-power laser facilities have been driven by the demonstration of the remarkable capability of pulsed light, leading to the development of a wide range of applications in energy, bioscience, and fundamental science. The continuous demand for higher energy and higher peak power requires optical components that can operate at very high fluence. In this context, the laser-induced damage threshold (LIDT) of optical coatings becomes one of the main limitations for the development of multi-petawatt laser systems. Two main approaches can be considered to overcome this limitation. The first one is to increase the beam size in order to reduce the fluence during the beam transport and focus the beam only at the final stage. However, this solution requires optics with sizes up to the meter scale, which creates strong constraints on the fabrication of highly uniform coatings over very large areas. The second approach is to develop optical coatings that can directly withstand higher fluence. This requires the fabrication of complex mirrors based on the deposition of tens of layers with nanometer-scale thickness control. Achieving high damage resistance while maintaining excellent optical performance makes the development of such mirrors particularly challenging for high-power laser facilities.
At ELI Beamlines, we installed an advanced coating chamber capable of producing meter-scale optics with very high uniformity. First results demonstrate the capability to deposit uniform gold coatings with high LIDT on large mirrors for efficient beam transport of our PW-kJ laser system. In parallel, we are developing innovative coatings using advanced deposition techniques such as High-Power Impulse Magnetron Sputtering in order to improve the laser-induced damage threshold. These two complementary approaches toward the development of optics for multi-petawatt lasers will be presented during this seminar.