Single-shot complete spatiotemporal Strehl ratio metrology of ultrashort laser pulses -- theory

TL;DR

This paper introduces a novel, single-shot method for accurately measuring the spatiotemporal Strehl ratio of ultrashort laser pulses, crucial for high-intensity laser experiments, using nonlinear effects like relativistic surface harmonic generation.

Contribution

The paper presents a new, simple analysis-based technique for complete spatiotemporal Strehl ratio metrology in ultrashort laser pulses, enabling precise peak intensity measurement.

Findings

Allows single-shot measurement of the spatiotemporal Strehl ratio

Diagnoses all types of temporal and spatial distortions

Can be implemented directly on target using relativistic surface harmonic generation

Abstract

Ultra-high intensity femtosecond lasers at focus are now routinely used for relativistic motion of charged particles with peak intensities over 10^18W/cm^2. Such high-field experiments are very sensitive to the value of the peak intensity. Therefore, precise knowledge of the pulse intensity is a key prerequisite for the correct interpretation of experimental data. Accurate measurement of energy, spectral and spatial profiles being well established, peak intensity evaluation then only requires the determination of the spatiotemporal Strehl ratio. Here I propose a new method based on a simple analysis of a nonlinear effect. It diagnoses all the temporal, spatial and spatiotemporal coupling distortions. This method can even be implemented on target by using relativistic surface harmonic generation for example.