Petawatt laser absorption bounded

TL;DR

This paper establishes theoretical bounds on laser energy absorption in petawatt laser-solid interactions, constraining the range of possible absorption fractions and guiding future target design for advanced applications.

Contribution

It introduces a relativistic Rankine-Hugoniot-like analysis revealing maximum and minimum absorption bounds in the petawatt regime, a novel theoretical insight.

Findings

Absorption has a theoretical maximum and minimum in petawatt laser interactions.

High absorption is forbidden at low laser power, and low absorption at high power.

Results guide the development of structured and multilayer targets.

Abstract

The interaction of petawatt ($10^{15}\ \mathrm{W}$) lasers with solid matter forms the basis for advanced scientific applications such as table-top particle accelerators, ultrafast imaging systems and laser fusion. Key metrics for these applications relate to absorption, yet conditions in this regime are so nonlinear that it is often impossible to know the fraction of absorbed light $f$, and even the range of $f$ is unknown. Here using a relativistic Rankine-Hugoniot-like analysis, we show for the first time that $f$ exhibits a theoretical maximum and minimum. These bounds constrain nonlinear absorption mechanisms across the petawatt regime, forbidding high absorption values at low laser power and low absorption values at high laser power. For applications needing to circumvent the absorption bounds, these results will accelerate a shift from solid targets, towards structured and multilayer targets, and lead the development of new materials.