Amplification and ellipticity enhancement of sub-femtosecond XUV pulses in IR-field-dressed neon-like active medium of a plasma-based X-ray laser

TL;DR

This paper presents a detailed analytical and numerical study of a method to amplify and enhance the ellipticity of sub-femtosecond XUV pulses generated by high-order harmonics in a plasma-based X-ray laser medium, with potential experimental applications.

Contribution

It introduces a new technique for amplifying and ellipticity-enhancing high-harmonic XUV pulses in a plasma medium, supported by analytical theory and numerical simulations.

Findings

Amplification of sub-femtosecond XUV pulse trains is achievable.

Ellipticity of high-harmonic radiation can be maintained or enhanced during amplification.

The method is feasible with neon-like Ti^{12+} ions and a 3.9 micron IR laser.

Abstract

In [I.R. Khairulin et al., submitted to Phys. Rev. Lett.] we propose a method for amplifying a train of sub-femtosecond pulses of circularly or elliptically polarized extreme ultraviolet (XUV) radiation, constituted by high-order harmonics of an infrared (IR) laser field, in a neon-like active medium of a plasma-based X-ray laser, additionally irradiated with a replica of a fundamental frequency laser field used to generate harmonics, and show the possibility of maintaining or enhancing the ellipticity of high-harmonic radiation during its amplification. In the present paper we describe this process in detail both for a single harmonic component and a sub-femtosecond pulse train formed by a set of harmonics. We derive the analytical theory and describe both analytically and numerically the evolution of the high-harmonic field during its propagation through the medium. We discuss also the possibility of an experimental implementation of the suggested technique in an active medium of an X-ray laser based on neon-like Ti^{12+} ions irradiated by an IR laser field with a wavelength of 3.9 microns.