NSF OPAL: Laser System Design and Critical Technologies*

Ultra-intense lasers are opening new frontiers in discovery science by driving processes with extreme optical fields. One promising approach to achieving focused intensities exceeding 5 x 10²³ W/cm² is through optical parametric chirped-pulse amplification at kilojoule energies, producing femtosecond pulses focused to few-micron spots. The NSF OPAL project is designing such a facility, which includes two beams, Alpha 1 and Alpha 2, each capable of 25-PW peak powers. These beams will be co-timed and co-pointed in various configurations to support flagship experiments. Additionally, a 1-PW Beta beam will be available instead of Alpha 2, providing more flexible focusing geometries and enabling synchronized electron beam generation for various experimental use cases.

While critical laser technologies have been demonstrated at the petawatt scale, scaling up to 25 PW requires significant aperture expansion to stay below the threshold for laser damage. The largest beam planned for the system (>80 cm, square profile) represents a 4.5-fold increase in single-beam area compared to high-energy laser beams like those of Omega EP or the National Ignition Facility. The presentation will provide an overview of the laser architecture, the critical laser technologies required, and the progress made towards delivering a preliminary laser design by the end of the three-year project. This material is based upon work supported by the U.S. National Science Foundation under Cooperative Agreement No. (PHY-2329970).