Polarization-assisted amplitude gating as a route to tunable, high-contrast attosecond pulses

Attosecond spectroscopy is a powerful technique for probing electron dynamics in fundamental systems. However, extending this method to cover a wide range of element-specific, core-hole transitions requires the availability of broadly tunable attosecond pulses. In this Letter, we present a new method for generating high-flux, high-contrast single attosecond pulses tunable across the range of 50-120 eV. The method is referred to as a Polarization ASSisted Amplitude GatE (PASSAGE) and uses a few-cycle driving pulse along with a partial polarization gate to extend the bandwidth of high harmonic emission in the temporally isolated, cut-off portion of the spectrum. The simplicity of this technique will help pave the way for implementing attosecond core-hole spectroscopy to probe more complex reactions and bring attosecond science into a multidisciplinary setting. (C) 2016 Optical Society of America