Generation of isolated attosecond pulses in the far field by spatial filtering with an intense few-cycle mid-infrared laser

TL;DR

This paper presents a theoretical method for generating isolated attosecond pulses using spatial filtering of high-order harmonics in the far field driven by intense few-cycle mid-infrared lasers, accounting for multi-electron effects and propagation.

Contribution

It introduces a novel approach combining spatial filtering and macroscopic propagation effects to produce isolated attosecond pulses with mid-infrared lasers.

Findings

Reshaping of the fundamental laser field creates continuum in HHG spectra.

Spatial filtering can isolate attosecond pulses in the far field.

Carrier-envelope-phase influences the quality and yield of the IAP.

Abstract

We report theoretical calculations of high-order harmonic generation (HHG) of Xe with the inclusion of multi-electron effects and macroscopic propagation of the fundamental and harmonic fields in an ionizing medium. By using the time-frequency analysis we show that the reshaping of the fundamental laser field is responsible for the continuum structure in the HHG spectra. We further suggest a method for obtaining an isolated attosecond pulse (IAP) by using a filter centered on axis to select the harmonics in the far field with different divergence. We also discuss the carrier-envelope-phase dependence of an IAP and the possibility to optimize the yield of the IAP. With the intense few-cycle mid-infrared lasers, this offers a possible method for generating isolated attosecond pulses.