Terahertz pulse generation by two-color laser fields with circular polarization

authored by

C. Tailliez, A. Stathopulos, S. Skupin, D. Buožius, I. Babushkin, V. Vaičaitis, L. Bergé

Abstract

We study the influence of the polarization states of ionizing femtosecond two-color pulses on the emitted terahertz radiation in gases. A local-current model and plane-wave evaluations justify the previously-reported impact on the THz energy yield and a (almost) linearly-polarized THz field when using circularly-polarized laser harmonics. For such pump pulses, the THz yield is independent of the relative phase between the two colors. When the pump pulses have same helicity, the increase in the THz yield is associated with longer ionization sequences and higher electron transverse momenta acquired in the driving field. Reversely, for two color pulses with opposite helicity, the dramatic loss of THz power comes from destructive interferences driven by the highly symmetric response of the photocurrents lined up on the third harmonic of the fundamental pulse. While our experiments confirm an increased THz yield for circularly-polarized pumps of same helicity, surprisingly, the emitted THz radiation is not linearly-polarized. This effect is explained by means of comprehensive 3D numerical simulations highlighting the role of the spatial alignment and non-collinear propagation of the two colors.

Organisation(s)

Institute of Quantum Optics
PhoenixD: Photonics, Optics, and Engineering - Innovation Across Disciplines

External Organisation(s)

French Alternative Energies and Atomic Energy Commission (CEA)
Université Paris-Saclay
Universite Claude Bernard Lyon 1
Vilnius University
Max Born Institute for Nonlinear Optics and Short Pulse Spectroscopy im Forschungsbund Berlin e.V. (MBI)

Type

Article

Journal

New journal of physics

Volume

22

ISSN

1367-2630

Publication date

16.10.2020

Publication status

Published

Peer reviewed

Yes

ASJC Scopus subject areas

Physics and Astronomy(all)

Electronic version(s)

https://doi.org/10.1088/1367-2630/abb863 (Access: Open)