Resonant enhancement of a single attosecond pulse in a gas medium by a time-delayed control field

TL;DR

This paper proposes a theoretical scheme for enhancing and controlling a single attosecond pulse in a helium gas medium using a time-delayed femtosecond laser, demonstrating potential for advanced attosecond optical control.

Contribution

It introduces a novel optical control method that enhances and shapes an attosecond pulse via a time-delayed laser coupling autoionizing states in helium.

Findings

Spectral and temporal distortion of the pulse was observed.

A narrowed, enhanced spectral spike appears under specific conditions.

The control scheme enables broadband photon wave packet manipulation.

Abstract

An optical coherent control scheme has been proposed and theoretically investigated where an extreme ultraviolet single attosecond pulse (SAP) propagates through a dense helium gas dressed by a time-delayed femtosecond laser pulse. The laser pulse couples the 2s2p(^1P) and 2s^2(^1S) autoionizing states when the SAP excites the 2s2p state. After going through the gas, the spectral and temporal profiles of the SAP are strongly distorted. A narrowed but enhanced spike in the spectrum shows up for specific intensities and time delays of the laser, which exemplifies the control of a broadband photon wave packet by an ultrashort dressing field for the first time. We analyze the photon and electron dynamics and conclude on the dressing condition that maximizes this enhancement. The result demonstrates new possibilities of attosecond optical control.