Table-top interferometry on extreme time and wavelength scales

TL;DR

This paper introduces a novel all-reflective Michelson interferometer for XUV spectroscopy, achieving attosecond precision and enabling advanced time-resolved measurements in the extreme ultraviolet range.

Contribution

It presents a compact, high-precision XUV autocorrelator operating over a broad spectral range, advancing ultrafast spectroscopy capabilities in the extreme ultraviolet.

Findings

Achieved single-digit attosecond autocorrelation resolution.

Demonstrated spectroscopic measurement of a sharp electronic transition in Argon.

Showed excellent agreement with high-resolution grating spectrometer results.

Abstract

High-resolution Fourier-transform spectroscopy using table-top sources in the extreme ultraviolet (XUV) spectral range is still in its infancy. In this contribution a significant advance is presented based on a Michelson-type all-reflective split-and-delay autocorrelator operating in a quasi amplitude splitting mode. The autocorrelator works under a grazing incidence angle in a broad spectral range $\mathrm{(10\,nm - 1\,\mu m)}$ providing collinear propagation of both pulse replicas and thus a constant phase difference across the beam profile. The compact instrument allows for XUV pulse autocorrelation measurements in the time domain with a single-digit attosecond precision resulting in a resolution of $\mathrm{E/\Delta E=2000}$. Its performance for spectroscopic applications is demonstrated by characterizing a very sharp electronic transition at $\mathrm{26.6\,eV}$ in Ar gas induced by the $\mathrm{11^{th}}$ harmonic of a frequency-doubled Yb-fiber laser leading to the characteristic $\mathrm{3s3p^{6}4p^{1}P^{1}}$ Fano-resonance of Ar atoms. We benchmark our time-domain interferometry results with a high-resolution XUV grating spectrometer and find an excellent agreement. The common-path interferometer opens up new opportunities for short-wavelength femtosecond and attosecond pulse metrology and dynamic studies on extreme time scales in various research fields.