Spatially Resolved Fourier Transform Spectroscopy in the Extreme Ultraviolet

TL;DR

This paper presents a novel, highly stable interferometry technique for Fourier transform spectroscopy in the extreme ultraviolet range, enabling spatially resolved measurements with sub-attosecond precision.

Contribution

It introduces an ultrastable common-path interferometer for XUV FTS, allowing controlled delay scanning and high coherence in the 17-55 nm range.

Findings

Achieved sub-attosecond timing stability in XUV pulse pairs

Demonstrated spatially resolved FTS on thin film materials

Produced fully coherent XUV pulse pairs with Gaussian spatial mode

Abstract

Coherent extreme ultraviolet (XUV) radiation produced by table-top high-harmonic generation (HHG) sources provides a wealth of possibilities in research areas ranging from attosecond physics to high resolution coherent imaging. However, it remains challenging to fully exploit the coherence of such sources for interferometry and Fourier transform spectroscopy (FTS). This is due to the need for a measurement system that is stable at the level of a wavelength fraction, yet allowing a controlled scanning of time delays. Here we demonstrate XUV interferometry and FTS in the 17-55 nm wavelength range using an ultrastable common-path interferometer suitable for high-intensity laser pulses that drive the HHG process. This approach enables the generation of fully coherent XUV pulse pairs with sub-attosecond timing variation, tunable time delay and a clean Gaussian spatial mode profile. We demonstrate the capabilities of our XUV interferometer by performing spatially resolved FTS on a thin film composed of titanium and silicon nitride.