Generation of a strong attosecond pulse train with an orthogonally polarized two-color laser field

Abstract

We theoretically investigate the high-order harmonic generation from a neon atom irradiated by an intense two-color femtosecond laser pulse, in which the fundamental field and its second harmonic are linearly polarized and orthogonal to each other. In contrast to usual high-harmonic generation with linearly polarized fundamental field alone, a very strong and clean high-harmonic spectrum, consisting of both odd and even orders of harmonics, can be generated in the orthogonally polarized two-color laser field with proper selection of the relative phase between the fundamental and second-harmonic fields. In time domain, this results in a strong and regular attosecond pulse train. The origin of these behaviors is elucidated by analyzing semiclassical electron paths and by simulating high-harmonic generation quantum mechanically.

Subcycle Control of Electron-Electron Correlation in Double Ionization

“…In OTC pulses time and space are connected and thus an attosecond time scale is established in the polarization plane for both the emitted and the recolliding wave packets [3,4]. OTC pulses have been proposed to increase the efficiency [5] and to allow control over the polarization state of high-harmonic radiation [6], and they have been used to interrogate atomic and molecular orbital structure [7][8][9] via high harmonic radiation. The ability to steer electrons with two-color laser fields has led to proposals for using them in laser induced electron diffraction [10] and double ionization [11,12].…”

Control of threshold enhancements in harmonic generation by atoms in a two-color laser field with orthogonal polarizations

“…A more promising HHG scheme for generation of intense XUV and attosecond pulses was suggested a decade ago [24][25][26][27] that involves a two-color pump field whose components are linearly polarized in orthogonal directions. If both components have comparable intensities, the yield of high-order harmonics can be enhanced and more intense attosecond pulses can be produced (as compared to a single frequency laser field) by adjusting the relative phase of the two components.…”

“…As emphasized in Refs. [24][25][26], variation of the relative phase of the two components can affect the number of contributing classical electron trajectories in the quasiclassical description of the propagation step of the HHG process. The ability to select trajectories was demonstrated experimentally in Refs.…”

Generation of an extreme ultraviolet supercontinuum in a two-color spatially inhomogeneous field

“…An alternative method for generating a broadband attosecond pulse is controlling quantum paths, which can significantly modulate the HHG process. In the single-atom response, the quantum path control can be realized using a two-color field [15,16,[25][26][27], an APT [28,29], an ultraviolet (UV) pulse [30,31], or a static electric field [32,33]. Macroscopically, the short path can be realized by the phase-matching condition [34] or spatial filtering [35].…”