Polarization shaping of high-order harmonics in laser-aligned molecules

TL;DR

This work demonstrates a method to generate short-pulse extreme ultraviolet radiation with controlled polarization by using high-order harmonics in pre-aligned molecules, enabling polarization shaping of the emitted light.

Contribution

The paper introduces a novel approach to control the polarization of high-order harmonics through molecular alignment and circularly polarized driving pulses.

Findings

Produced EUV radiation with high ellipticity close to circular

Controlled the polarization state by adjusting molecular angular distribution

Validated the polarization shaping technique experimentally

Abstract

The present work reports on the generation of short-pulse coherent extreme ultraviolet radiation of controlled polarization. The proposed strategy is based on high-order harmonics generated in pre-aligned molecules. Field-free molecular alignment produced by a short linearly-polarized infrared laser pulse is used to break the isotropy of a gas medium. Driving the aligned molecules by a circularly-polarized infrared pulse allows to transfer the anisotropy of the medium to the polarization of the generated harmonic light. The ellipticity of the latter is controlled by adjusting the angular distribution of the molecules at the time they interact with the driving pulse. Extreme ultraviolet radiation produced with high degree of ellipticity (close to circular) is demonstrated.