Petawatt lasers go beyond the limits of human imagination in every respect.

All over the world, scientists use high-power lasers that release incredibly high amounts of energy in extremely short pulses. They are pursuing goals as diverse as the research of nuclear fusion and the development of new methods for early cancer detection.  

The most well-known facilities of this kind include the National Ignition Facility (NIF) at Lawrence Livermore National Laboratory in the USA, the Mégajoule laser in France, and the ATLAS laser at the Centre for Advanced Laser Applications in Garching near Munich. The amount of energy generated by these systems is in the petawatt range, which is equal to one quadrillion watts. The most powerful laser pulse to date was achieved in 2015 at the LFEX laser at Osaka University and was 2 PW. This power can only be achieved by concentrating comparatively moderate amounts of energy (in the case of the ATLAS laser: 60 J) on tiny areas for very short periods of time (usually in the femtosecond range (10^-15 seconds)). This achieves approximately the same effect as focusing the entire solar radiation arriving on Earth at a given time on the tip of a pin.

To achieve the corresponding energy, we had to go big. For example, the laser beams generated by the French laser Mégajoule are done so in 22 beamlines. The four halls in which these are housed together take up about as much space as two soccer fields. A total of 10,000 optics in various dimensions are used to guide the beams. Since the laser optics have to withstand immense power, the substrates are significantly thicker and the diameters larger than those of laser systems in industry. Even more important is the coating: its damage threshold power must be around 5 J/cm² for a pulse of 300 picoseconds. Even more emphasis is placed on reliable quality than in conventional lasers because several thousand individual components make troubleshooting a complex challenge.