Design of Novel Optical Cavities for Strong Shock Compression

Laser-induced strong shock waves with high efficiency remain a technical challenge, evidenced by the effort invested at large-scale national laboratories to optimize the laser-induced shock compression of pellets of light elements. Here, we present theoretical work on designing novel optical cavities for strong shock generation at a tabletop scale. The key idea is to utilize multiple laser pulses spatially and temporally shaped to form concentric laser rings on condensed matter samples. Each laser ring launches a 2D focusing pressure wave that converges at a common central point. The pulses are delayed in the nanosecond range and spaced by microns, matching the laser scanning speed to the shock wave speed, typically several \textmu m/ns in condensed matter, allowing amplification of the pressure waves through superposition. The herein-described optical cavities are expected to maintain or even exceed the shock excitation efficiency of $10^4$ GPa/J reported in our previous work using a single laser ring, where the limiting factor in generating stronger shocks was the saturation of input laser energy. The current design for multiple laser rings bypasses the saturation due to much larger excitation areas; thus, the total input laser energy can be dramatically increased. We further experimentally show that dielectric metasurfaces can combine all optics for forming the required clean high-fluence laser rings in a single optics. Our work provides a viable pathway toward applying laser-induced strong shock compression of condensed matter. The current tabletop scheme caters to the need of the shock compression community by providing the flexibility to test new shock compression strategies.