Attosecond pulse production using resonantly-enhanced high-order harmonics

TL;DR

This paper theoretically investigates how resonant effects in xenon can synchronize high-order harmonics to produce shorter, more intense attosecond pulses, with potential enhancements in efficiency and pulse duration control.

Contribution

It introduces a method to exploit resonant dephasing compensation for harmonic synchronization, enabling significant attosecond pulse shortening and intensity enhancement.

Findings

Resonant dephasing can compensate phase differences in harmonics.

Synchronization leads to over tenfold increase in pulse intensity.

Two-color driving fields further boost harmonic efficiency.

Abstract

We study theoretically the effect of the giant resonance in Xe on the phase difference between the consecutive high order resonantly-enhanced harmonics and calculate the duration of the attosecond pulses produced by these harmonics. For certain conditions resonantly-induced dephasing compensates the phase difference which is intrinsic for the off-resonance harmonics. We find these conditions analytically and compare them with the numerical results. This harmonic synchronization allows attosecond pulse shortening in conjunction with the resonance-induced intensity increase by more than an order of magnitude; the latter enhancement relaxes the requirements for the UV filtering needed for the attosecond pulse production. Using a two-color driving field allows further increase of the intensity. In particular, a caustic-like feature in the harmonic spectrum leads to the generation efficiency growth up to two orders of magnitude, however accompanied by an elongation of the XUV pulse.