# Single-shot fourth-order auto-correlator

## TL;DR

This paper introduces a novel single-shot fourth-order auto-correlator that significantly improves temporal contrast measurement of ultra-high intense laser pulses, achieving higher dynamic range and better time resolution than previous third-order methods.

## Contribution

The paper presents a new single-shot fourth-order auto-correlator that enhances temporal contrast characterization with higher dynamic range and temporal resolution compared to existing third-order correlators.

## Key findings

- Achieved a dynamic range of approximately 10^11 in experiments.
- Demonstrated a time resolution of approximately 160 fs.
- Successfully measured the temporal contrast of a PW laser system in single-shot.

## Abstract

The temporal contrast is one of the most important parameters of an ultra-high intense laser pulse. Third-order auto-correlator or cross-correlator have been widely used to characterize the temporal contrast of an ultra-intense laser pulse in the past decades. Here, a novel and simple single-shot fourth-order auto-correlator to characterize the temporal contrast with higher time resolution and better pulse contrast fidelity in comparison to third-order correlators is proposed. The single-shot fourth-order autocorrelation consists of a frequency degenerate four-wave mixing process and a sum-frequency mixing process. The proof-of-principle experiments show that a dynamic range of approximately 10^11 compared with the noise level, a time resolution of approximately 160 fs, and a time window of 65 ps can be successfully obtained using the novel single-shot fourth-order auto-correlator, which is the highest dynamic range with simultaneous high time resolution for single-shot temporal contrast measurement so far. Furthermore, the temporal contrast of laser pulse from a PW laser system is successfully measured in single-shot with a dynamic range of about 2*10^10 and simultaneous a time resolution of 160 fs.

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Source: https://tomesphere.com/paper/1906.10301