High-power laser beam shaping using a metasurface for shock excitation and focusing at the microscale

TL;DR

This paper introduces a novel optical design using dielectric metasurfaces to generate high-pressure shock waves at the microscale, enabling tabletop laser shock experiments with high efficiency and repeatability.

Contribution

The study demonstrates the use of damage-threshold metasurfaces for high-power laser focusing and models a new approach for shock wave generation through laser ring focusing.

Findings

Successful experimental demonstration of laser rings on water sample.

Metasurfaces with a damage threshold of 1.1 J/cm2 enable high-fluence laser rings.

Achieved shock pressures in the gigapascal range.

Abstract

Achieving high repeatability and efficiency in laser-induced strong shock wave excitation remains a significant technical challenge, as evidenced by the extensive efforts undertaken at large-scale national laboratories to optimize the compression of light element pellets. In this study, we propose and model a novel optical design for generating strong shocks at a tabletop scale. Our approach leverages the spatial and temporal shaping of multiple laser pulses to form concentric laser rings on condensed matter samples. Each laser ring initiates a two-dimensional focusing shock wave that overlaps and converges with preceding shock waves at a central point within the ring. We present preliminary experimental results for a single ring configuration. To enable high-power laser focusing at the micron scale, we demonstrate experimentally the feasibility of employing dielectric metasurfaces with exceptional damage threshold, experimentally determined to be 1.1 J/cm2, as replacements for conventional optics. These metasurfaces enable the creation of pristine, high-fluence laser rings essential for launching stable shock waves in materials. Herein, we showcase results obtained using a water sample, achieving shock pressures in the gigapascal (GPa) range. Our findings provide a promising pathway towards the application of laser-induced strong shock compression in condensed matter at the microscale.