Tabletop superposed laser shocks: 10 GPa nondestructively and >100 GPa with  < 100 mJ laser pulse energy

Laser shock generation is well established across a very wide range of shock pressures. Two important limitations in most cases are laser-induced sample damage, which limits the shock pressure that can be reached nondestructively, and laser pulse energy and intensity, which limit the shock pressure that can be reached even when sample damage is permissible. We have significantly mitigated these limitations through the use of shock wave superposition. Using several dozen parallel lines of pulsed laser light that arrive at a sample in succession with nanosecond temporal delays and micron spatial delays between adjacent lines, we have launched surface acoustic waves that grow to GPa strains when the delays are adjusted to match the propagating wave velocity [1]. Each excitation pulse is low enough in intensity and fluence to avoid sample damage. We have used a similar strategy with four concentric circular rings of pulsed laser light that arrive at a sample in similar succession with the largest-diameter ring arriving first to launch a focusing shock and the successively smaller-diameter rings arriving just as the shock converges to their diameters in order to build up the shock pressure through the combination of wave focusing and superposition. This extends shock generation with a single ring-shaped pulse [2]. In both cases pressures of about 10 GPa can be reached nondestructively using only a few mJ total laser pulse energy. Using up to 50 mJ total pulse energy in the shock focusing configuration, pressures of about 1000 GPa (1 Mbar) can be reached at the shock focus. This approach enables extreme conditions to be reached with a simple tabletop laser. The methods exploit experimental geometries in which the shock propagates laterally relative to the direction of the optical beams, allowing continuous direct optical access to the shock for additional optical pumping and for real-time optical monitoring (in nearly any spectral range from THz to x-ray) of the shock and material responses to it.

[1] “Additive laser excitation of giant nonlinear surface acoustic wave pulses,” J. Deschamps, et al., Phys. Rev. Appl. 20, 044044 (2023).

[2] "Anomalous fracture behavior in borosilicate glass facilitated by stress-induced molecular rearrangements," J. Lem, et al., PNAS 122, e2516249122 (2025).