Table-top interferometry on extreme time and wavelength scales

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 $(10\mathrm{nm}-1\hat{\mathrm{I}}¼\mathrm{m})$ 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 $E/\hat{\mathrm{I}}”\mathrm{E}=2000$. Its performance for spectroscopic applications is demonstrated by characterizing a very sharp electronic transition at $26.6\mathrm{eV}$ in Ar gas induced by the $11^{\mathrm{th}}$ harmonic of a frequency-doubled Yb-fiber laser leading to the characteristic $3s3{\mathrm{p}}^{6}4{\mathrm{p}}^1{\mathrm{P}}^1$ 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.

9 pages, 4 figures