Light Pulses With Few Optical Cycles Break Through The 300 W Barrier

A team led by researchers from the Max Born Institute for Nonlinear Optics and Short Pulse Spectroscopy (MBI), the Laser Laboratory Göttingen (LLG) and the Active Fiber Systems (AFS) has multi-millijoule 3-cycle pulses with a average power of 318 W generated.

These results represent an important milestone in laser technology and pave the way for industrial applications. The report appeared in "Optica" as a memorandum.

Extremely short pulses of light with only a few oscillations of the electromagnetic field are among the fastest events humanity has ever produced. Although the first light pulses were produced with few optical cycles about 30 years ago, they could only be used in cutting-edge research, eg for time-resolved studies or the generation of attosecond pulses. In order to find its way into industrial applications, a number of major challenges have to be tackled, such as fully automatic operation and energy and performance upscaling of the sources.

The scientists from MBI, LLG and AFS followed a novel approach by compressing 300 fs pulses from a high-energy, high-power laser system directly for a few cycles. This requires 30x compression, which has only recently become possible through the introduction of stretched, flexible hollow fiber technology, which provides virtually unlimited length scalability. The study used a coherently combined multichannel fiber laser with up to 10 mJ pulses with up to 1 kW average power as the light source. This system is currently being developed by AFS for the large European ELI ALPS laser plant in Szeged, Hungary. Pulse compression used a 6 meter long, stretched, flexible hollow fiber co-developed by MBI and LLG. As the pulses propagate through argon gas filled in the hollow waveguide, a nonlinear interaction between the intense light and the gas atoms occurs, widening the spectrum. The pulses with a much broadened spectrum can then be compressed to a shorter duration by compensating their spectral phase with a set of chirped mirrors. In this way, the team was able to generate 10 mF, 100 fs pulses with 100 kHz repetition rate at an average power of 318 W, which is the highest average power ever achieved by a laser with few cycles. The pulses with a much broadened spectrum can then be compressed to a shorter duration by compensating their spectral phase with a set of chirped mirrors. In this way, the team was able to generate 10 mF, 100 fs pulses with 100 kHz repetition rate at an average power of 318 W, which is the highest average power ever achieved by a laser with few cycles. The pulses with a much broadened spectrum can then be compressed to a shorter duration by compensating their spectral phase with a set of chirped mirrors. In this way, the team was able to generate 10 mF, 100 fs pulses with 100 kHz repetition rate at an average power of 318 W, which is the highest average power ever achieved by a laser with few cycles.

This performance shows that high-performance, industrial-grade lasers can be brought into the low-cycle regime using stretched flexible hollow fiber technology. This opens up new possibilities for industrial applications, such as highly parallelized material processing.