Abstract

Generation of an elliptically polarized attosecond pulse train by an orthogonally polarized two-color (OTC) laser field is investigated theoretically and simulated numerically. The OTC field consists of two linearly polarized fields with orthogonal polarizations and frequencies that are integer multiples of the fundamental frequency $\omega$. For the $\omega - 3\omega$ OTC field, the emitted harmonics are elliptically polarized so that they may form an elliptically polarized attosecond pulse train provided that a group of harmonics is phase-locked. This is the case if only one quantum orbit generates the corresponding part of the harmonic spectrum. If so, then two attosecond pulses are emitted per optical cycle due to the dynamical symmetry of the $\omega - 3\omega$ OTC field. Atomic targets with an $s$ ground state only generate attosecond pulses with almost linear polarization. Using, however, targets with a $p$ ground state, attosecond pulses with substantial ellipticity can be produced because ground states with opposite magnetic quantum numbers $m = + 1$ and $m = - 1$ produce harmonics with opposite helicities at different rates. In this case, the harmonic intensity and harmonic ellipticity are different for the ground states with the magnetic quantum number $m = \pm 1$. These differences are the source of the attosecond pulse ellipticity and can be controlled using the relative phase as a control parameter. In addition, by choosing a particular group of harmonics, one can select the desired ellipticity of the attosecond pulse train.

© 2021 Optical Society of America

Generation of isolated circularly polarized attosecond pulses by three-color laser field mixing

Renzhi Shao, Chunyang Zhai, Yinfu Zhang, Ning Sun, Wei Cao, Pengfei Lan, and Peixiang Lu
Opt. Express 28(11) 15874-15884 (2020)

Attosecond pulse generation by a two-color field

Vladimir D. Taranukhin
J. Opt. Soc. Am. B 21(2) 419-424 (2004)

Theoretical investigation of single attosecond pulse generation in an orthogonally polarized two-color laser field

Yongli Yu, Xiaohong Song, Yuxi Fu, Ruxin Li, Ya Cheng, and Zhizhan Xu
Opt. Express 16(2) 686-694 (2008)

Bayesian optimal control of the ultrashort circularly polarized attosecond pulse generation by two-color polarization gating

Chon-Teng Belmiro Chu, Yae-Lin Sheu, and Shih-I Chu
Opt. Express 29(21) 32900-32909 (2021)

Generation of the isolated highly elliptically polarized attosecond pulse using the polarization gating technique: TDDFT approach

Ahmad Reza madhani, Elnaz Irani, and Mohammad Monfared
Opt. Express 31(11) 18430-18443 (2023)