Enhanced harmonic generation in extended molecular systems by two-color excitation

Bandrauk, André D.; Chelkowski, Szczepan; Yu, Huafeng; Constant, Éric

doi:10.1103/physreva.56.r2537

Cited by 110 publications

(76 citation statements)

References 23 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…Some years ago, mechanism (i) has been suggested as a new mechanism of HHG in stretched molecules [16,17,18], and a cutoff at 8U p + I p was derived for the special internuclear distances R = (2n + 1)πα, n = 0, 1 . .…”

mentioning

confidence: 99%

Ultrahigh Harmonics from Laser-Assisted Ion-Atom Collisions

Lein

Rost

2003

Phys. Rev. Lett.

View full text Add to dashboard Cite

We present a theoretical analysis of high-order harmonic generation from ion-atom collisions in the presence of linearly polarized intense laser pulses. Photons with frequencies significantly higher than in standard atomic high-harmonic generation are emitted. These harmonics are due to two different mechanisms: (i) collisional electron capture and subsequent laser-driven transfer of an electron between projectile and target atom; (ii) reflection of a laser-driven electron from the projectile leading to recombination at the parent atom.PACS numbers: 42.65. Ky,34.50.Rk,32.80.Rm,34.70+e Over the last decades, a vast amount of work has been devoted to the study of ion-atom collisions [1] Kirchner [7] investigate fast collisions in the presence of a strong laser field. In Ref.[6], excitation mechanisms are discussed, while Ref. [7] focuses on ionization and electron capture. In both cases, the presence of the field leads to a significant modification of the collision process. On the other hand, there has been no study on the question how typical strong-field processes in atoms, such as high-order harmonic generation (HHG) [8] and above-threshold ionization [9], are modified due to the impact of an ion projectile. In HHG, a large number of incoming laser photons are converted into a single high-energy photon. HHG experiments are presently pursued with great effort [10,11] since the process serves as a source of coherent XUV radiation and attosecond pulses.In the present work, we investigate HHG in laserassisted ion-atom collision. We focus on impact velocities such that the time-scales of nuclear and electronic motion are comparable, i.e., we have significant probabilities for collisional electron transfer from the target to the projectile. For sufficiently long laser pulse durations, the laser-driven electron effectively sees a large range of internuclear distances during one laser pulse. When the laser polarization axis is parallel to the ion impact velocity, we show that this situation results in the generation of high harmonics with photon energies much higher than usually obtained in atomic HHG.The classical recollision model [12] describes atomic HHG as a sequence of strong-field ionization, acceleration of the electron in the laser field and recombination with the core. Within this model, the maximum return energy of the laser-driven electron is 3.17U p where2 ) is the ponderomotive potential for a laser with field amplitude E 0 and frequency ω. The maximum energy of the emitted photons is then equal to 3.17U p +I p where I p is the atomic ionization potential. For ion-atom collisions, we show below how the interplay between collisional electron capture and laser-driven electron transfer between target and projectile leads to new mechanisms of HHG with cutoffs at significantly higher energies.We consider collisions of protons on hydrogen atoms for proton energies of 2 keV (impact velocity v = 0.283 a.u.). Due to the large impact momentum, the projectile trajectory is assumed to be classical and along a s...

show abstract

mentioning

confidence: 99%

Ultrahigh Harmonics from Laser-Assisted Ion-Atom Collisions

Lein

Rost

2003

Phys. Rev. Lett.

View full text Add to dashboard Cite

show abstract

“…An alternative novel method for producing attosecond pulse has been turn to the use of two-or three-color laser field that allowed for using of longer driving laser and thus can avoid the stringent requirement for an available ultrafast laser source (sub-5 fs) in the single field. With the two-or three-color method, the attosecond pulse duration can also be decreased in analogy to the ideal sub-5 fs driving pulse [11][12][13]. The physics behind this phenomenon is that the HHG is a highly nonlinear optical process, which is sensitive to a slight change in the driving laser field [14].…”

Section: Introductionmentioning

confidence: 99%

A single isolated sub-50 attosecond pulse generation with a two-color laser field by a frequency-chirping technique

Zhao

Chu

2011

Chemical Physics Letters

View full text Add to dashboard Cite

“…On the microscopic single-atom (or local cluster) interaction level, the use of two-color fields to enhance the intensities of harmonic spectra (such as by increasing ionization rates or by favoring short trajectories while suppressing long trajectories, etc.) has been investigated for more than two decades [19][20][21][22][23][24][25][26]. Recently, as a result of advances in optical technology, there has been renewed interest in HHG driven by two-color (or multicolor) laser pulses owing to the possibility of subcycle waveform control in the synthesis of such pulses [9,27].…”

Section: Introductionmentioning

confidence: 99%

Enhancing high-order-harmonic generation by time delays between two-color, few-cycle pulses

Peng

Frolov

et al. 2017

Phys. Rev. A

View full text Add to dashboard Cite

Use of time delays in high-order-harmonic generation (HHG) driven by intense two-color, few-cycle pulses is investigated in order to determine means of optimizing HHG intensities and plateau cutoff energies. Based upon numerical solutions of the time-dependent Schrödinger equation for the H atom as well as analytical analyses, we show that introducing a time delay between the two-color, few-cycle pulses can result in an enhancement of the intensity of the HHG spectrum by an order of magnitude (or more) at the cost of a reduction in the HHG plateau cutoff energy. Results for both positive and negative time delays as well as various pulse carrier-envelope phases are investigated and discussed.

show abstract

Enhanced harmonic generation in extended molecular systems by two-color excitation

Cited by 110 publications

References 23 publications

Ultrahigh Harmonics from Laser-Assisted Ion-Atom Collisions

Ultrahigh Harmonics from Laser-Assisted Ion-Atom Collisions

A single isolated sub-50 attosecond pulse generation with a two-color laser field by a frequency-chirping technique

Enhancing high-order-harmonic generation by time delays between two-color, few-cycle pulses

Contact Info

Product

Resources

About