HotLoop Optimization of Petawatt Laser Focal Spot via a Twin-Focus Scheme

TL;DR

This paper introduces HotLoop, an in-situ wavefront correction method that optimizes petawatt laser focal spots, significantly improving intensity and proton acceleration outcomes.

Contribution

The work presents a twin-focus diagnostic scheme and HotLoop correction technique to enhance petawatt laser focusing and performance.

Findings

Achieved a Strehl ratio of 0.80 at 1 PW laser pulses.

Significantly increased cutoff proton energies in laser proton acceleration.

Demonstrated the importance of in-situ wavefront correction for high-intensity lasers.

Abstract

Achieving diffraction-limited focusing of high-power laser pulses to generate ultra-high intensities is crucial for developing compact laser-driven particle accelerators and exploring strong-field quantum electrodynamics. However, accurately diagnosing and optimizing the focal spots of petawatt (PW) laser pulses remains a significant challenge. In this work, we present an experimental methodology utilizing a twin-focus scheme to precisely characterize the intensity distribution and wavefront of focused PW femtosecond laser pulses, and employ it to elucidate their power-dependent evolution. Furthermore, we optimized the focal spots at full power via our in-situ wavefront correction method termed ``HotLoop', achieving a Strehl ratio of 0.80 for 1 PW laser pulses. Consequently, the cutoff proton energies in laser proton acceleration experiments were significantly enhanced. The success of this approach underscores the necessity of in-situ high-energy wavefront correction for ultra-high intensity laser-matter interactions.