# Interferometry for full temporal reconstruction of laser-plasma accelerator-based seeded free electron lasers

## TL;DR

This paper demonstrates how interferometry can be used to fully reconstruct the temporal and spectral properties of laser-plasma accelerator-based seeded free electron laser pulses in a single shot, aiding their development.

## Contribution

It introduces a novel interferometric method for complete spectro-temporal characterization of LPA-based seeded FEL pulses using numerical simulations and analytical models.

## Key findings

- Interferometric patterns reveal detailed FEL pulse properties.
- Single-shot reconstruction of spectro-temporal content is possible.
- Method can handle singular spatio-spectral distributions.

## Abstract

The spectacular development of Laser-Plasma Accelerators (LPA) appears very promising for a free electron laser application. The handling of the inherent properties of those LPA beams already allowed controlled production of LPA-based spontaneous undulator radiation. Stepping further, we here unveil that the forthcoming LPA-based seeded FELs will present singular spatio-spectral distributions. Relying on numerical simulations and simple analytical models, we show how those interferometric patterns can be exploited to retrieve, in single-shot, the spectro-temporal content and source point properties of the FEL pulses.