High-order harmonic generation of N ₂ molecule in two-color circularly polarized laser fields

Abstract

The generation of high-order harmonics and the attosecond pulse of the N2 molecule in two-color circularly polarized laser fields are investigated by the strong-field Lewenstein model. We show that the plateau of spectra is dramatically extended and a continuous harmonic spectrum with the bandwidth of 113 eV is obtained. When a static field is added to the x direction, the quantum path control is realized and a supercontinuum spectrum can be obtained, which is beneficial to obtain a shorter attosecond pulse. The underlying physical mechanism is well explained by the time–frequency analysis and the semi-classical three-step model with a finite initial transverse velocity. By superposing several orders of harmonics in the combination of two-color circularly polarized laser fields and a static field, an isolated attosecond pulse with a duration of 30 as can be generated.

Effects of initial electronic state on vortex patterns in counter-rotating circularly polarized attosecond pulses*

“…[5] The ultrashort attosecond pulses can also induce electron charge migration, thus offering the possibility for probing the molecular structure and imaging the molecular reactions. [6][7][8] In the research, a variety of pulses and their combinations have been used to explore electron dynamics, including the high-order harmonic generation (HHG), [9][10][11][12][13][14] nonsequential double ionization (NSDI), [15][16][17][18] and the photoelectron momentum distribution (PMD). [19][20][21][22][23] Recently it was found that single ionization of atom by two oppositely circularly polarized, time-delayed attosecond pulses produce vortex patterns in PMDs, [24][25][26][27] which are sensitive to the time delay between the pulses, their handedness, and their relative phase.…”

Electron-atom potential scattering in a corotating bicircular laser field

“…The atomic HHG process driven by a counter-rotating bicircular laser field was first theoretically considered in [33][34][35] and further investigated in the subsequent years [36][37][38][39]. More recently, the atomic and molecular HHG processes generated by a bicircular laser field have been investigated, both theoretically and experimentally in [30,32,[40][41][42][43][44][45][46][47][48][49][50][51][52][53]. It was also shown that it is possible to introduce spin into attoscience with spinpolarized electrons produced by a bicircular laser field [54].…”

High-order harmonic generation in polyatomic molecules induced by a bicircular laser field

“…Other atomic processes in strong bicircular fields were also investigated, such as strong-field ionization [43][44][45][46][47], laser-assisted recombination [20], nonsequential double ionization [48], the possibility of introducing spin into attoscience [49], etc. Molecular HHG using a bicircular field was studied in [50][51][52]. arXiv:1607.01773v1 [physics.atom-ph] 6 Jul 2016…”