Results in Physics (Feb 2023)
Generation of elliptically polarized isolated attosecond pulses from N2 and O2 molecules in orthogonal few-cycle two-color fields
Abstract
We theoretically study the generation of high-order harmonics and ultrashort isolated attosecond (as) pulses (IAPs) with large ellipticity from the perfectly aligned N2 and O2 molecules driven by the few-cycle orthogonally polarized two-color (OTC) field by numerically solving the reduced two-dimensional time-dependent Schrödinger equation (2D-TDSE). We show that the ellipticity of high-order harmonics strongly depends on the alignment angle and the amplitude ratio of the few-cycle OTC fields. Furthermore, high-order harmonics with large ellipticity are generated at proper alignment angles where ionization events mainly happens at larger laser ellipticities, namely when electrons distribute along the crossing lines in Lissajous diagram of the OTC fields. By superposing the supercontinuum harmonics from N2 and O2 molecules at proper alignment angles, we can directly produce the elliptically polarized IAPs with ellipticity up to 0.76 and the shortest one achieves 141 as. This work demonstrates the possibility for generating the elliptically polarized IAPs with large ellipticity using high-order harmonics from the aligned N2 and O2 molecules exposed to the few-cycle OTC fields.
