Helicity reversion in high-order-harmonic generation driven by bichromatic counter-rotating circularly polarized laser fields

Zhang, Xiaofan; Li, Liang; Zhu, Xinxin; Liu, Xi; Zhang, Qingbin; Lan, Pengfei; Lu, Peixiang

doi:10.1103/physreva.94.053408

Cited by 21 publications

(18 citation statements)

References 60 publications

(87 reference statements)

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“…In the mid-plateau, the right-handed emission from the p + orbital dominates, giving an overall right-handed spectrum, but its contribution drops slightly faster than the p − emission, which dominates closer to the harmonic cutoff. This effect can also be seen on numerical simulations [18,19] and its appearance here in calculations with only the short quantum orbit (with the second return producing harmonics over one order of magnitude weaker, as seen in Fig. 2(c)) provides an alternative to the existing explanations based on the second return's slightly higher harmonic cutoff at excursion times around 300 • /ω [18].…”

Section: Harmonic Spectra and Polarizationsupporting

confidence: 67%

“…This effect can also be seen on numerical simulations [18,19] and its appearance here in calculations with only the short quantum orbit (with the second return producing harmonics over one order of magnitude weaker, as seen in Fig. 2(c)) provides an alternative to the existing explanations based on the second return's slightly higher harmonic cutoff at excursion times around 300 • /ω [18].…”

Section: Harmonic Spectra and Polarizationsupporting

confidence: 67%

“…It therefore came as a surprise when experiments showed a definite asymmetry between the two helicities in the plateau harmonics, with a preference for right-handed harmonics that co-rotate with the lowerfrequency driver [10,14,15]. There is some debate over the origin of this asymmetry, since it can have a macroscopic origin from chiral phase-matching properties [16]; on the other hand, it is also present in numerical simulations of the time-dependent Schrödinger equation [15,[17][18][19], so it appears to come from both microscopic and macroscopic effects.…”

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confidence: 99%

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Strong-field approximation in a rotating frame: High-order harmonic emission from p states in bicircular fields

Pisanty

Jiménez-Galán

2017

Phys. Rev. A

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High-order harmonic generation with bicircular fields -the combination of counter-rotating circularly polarized pulses at different frequencies -results in a series of short-wavelength XUV harmonics with alternating circular polarizations, and experiments show that there is an asymmetry in the emission between the two helicities: a slight one in helium, and a larger one in neon and argon, where the emission is carried out by p-shell electrons.Here we analyze this asymmetry by switching to a rotating frame in which the field is linearly polarized; this induces an effective magnetic field which lowers the ionization potential of the p + orbital that co-rotates with the lower-frequency driver, enhancing its harmonic emission and the overall helicity of the generated harmonics, while also introducing nontrivial effects from the transformation to a non-inertial frame in complex time. In addition, this analysis directly relates the small asymmetry produced by s-shell emission to the imaginary part of the recollision velocity in the standard strong-field-approximation formalism.Light is one of our main tools for the investigation of the internal structure of dynamics of matter, and in this role we employ all of its characteristics: its spatial and temporal aspects, its coherence as a wave phenomenon, and its polarization as a vector effect. As we probe deeper into the structures of materials and molecules, and as we look with increasing detail at their dynamics, it becomes necessary to use higher frequencies and shorter pulses, and here the process of high-order harmonic generation (HHG) stands out as a simple and effective way to produce bright, short, coherent pulses of high-frequency radiation [1].The process of HHG is essentially driven by the ionization of gases by a strong, long-wavelength laser pulse, which then drives the photoelectron back to its parent ion with a high energy, which it emits as a single photon. This permits a large flexibility in the emission process, and its sub-laser-cycle nature allows us to probe atomic and molecular systems at their own timescales. Unfortunately, however, its collision-driven nature has long left unavailable one of the crucial tools in the toolbox -the use of circular polarizations [2].A number of attempts have been made over the years to produce high-order harmonics with circular or elliptical polarization [3][4][5][6][7][8], which would enable detailed time-resolved studies of magnetic materials and chiral molecules, but they have generally suffered from complex configurations, low efficiencies, and limited harmonic ellipticities. These limitations were recently overcome by combining counter-rotating circularly polarized drivers [9,10], in a so-called 'bicircular' configuration; this produces fully circular harmonics at similar efficiency to linear-polarization schemes, and it can be implemented with minimal modifications to existing beamlines [11].The simplest configuration uses drivers with equal intensities at frequencies ω 1 = ω and ω 2 = 2ω, in which case the field...

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Section: Harmonic Spectra and Polarizationsupporting

confidence: 67%

Section: Harmonic Spectra and Polarizationsupporting

confidence: 67%

mentioning

confidence: 99%

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Strong-field approximation in a rotating frame: High-order harmonic emission from p states in bicircular fields

Pisanty

Jiménez-Galán

2017

Phys. Rev. A

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“…The dynamical form of the nonlinear Hall effect manifests in the second harmonic transverse current in response to the linearly polarized light in noncentrosymmetric 2D materials such as biased single and few layer WTe 2 [56][57][58][59][60][61]. Interestingly, theoretical studies provide the direct correspondence of high harmonic helicity (circular dichroism) and topological nature of the electronic band structure [62,63]. For instance, it has been shown that the nonlinear helicity spectroscopy can sharply distinguish between trivial and topological phases of the Haldane model in the hexagonal 2D materials [64,65].…”

Section: Introductionmentioning

confidence: 99%

Second Harmonic Helicity and Faraday Rotation in Gated Single-Layer 1T$'$-WTe$_2$

Bhalla,

Rostami

2022

Preprint

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“…It has been found that circularly polarized coherent short wavelength harmonics can be generated by intense counter-rotating bichromatic circularly polarized femtosecond pulses due to the enhancement of electron recollision with parent ions. − This capability was demonstrated experimentally only recently , with a potential application to ultrafast X-ray magnetic circular dichroism . There have been many efforts in experiment and theory that are devoted to achieving circularly polarized HHG and attosecond pulses in atoms. − Recently, harmonics from degenerate current-carrying orbitals by bichromatic counterrotating circularly polarized pulses have been studied . HHG from 2D solid materials by bicircular fields has been proposed, and it is found that the harmonic polarization depends on the bandgap.…”

Section: Introductionmentioning

confidence: 99%

Signature of Molecular Orbital Symmetry in High-Order Harmonic Generation by Bichromatic Circularly Polarized Laser Pulses

2021

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Molecular orbital symmetry is shown to be an important factor in determining orders and helicities (polarizations) of high-order harmonic generation (HHG) by intense femtosecond counter-rotating bichromatic circularly polarized laser pulses. Numerical solutions of time-dependent Schrödinger equations (TDSE) for the one-electron molecular ions H2 + and H3 2+ for different initial electronic states show that harmonic orders and helicities are dependent on orbital symmetries and of the net incident pulse electric field. The numerical results and properties of the harmonics are described by dynamical symmetry theory and time profile analysis of the high-order harmonics, thus confirming that orbital and laser pulse symmetry dependence are generic in HHG of molecules.

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Helicity reversion in high-order-harmonic generation driven by bichromatic counter-rotating circularly polarized laser fields

Cited by 21 publications

References 60 publications

Strong-field approximation in a rotating frame: High-order harmonic emission from p states in bicircular fields

Strong-field approximation in a rotating frame: High-order harmonic emission from p states in bicircular fields

Second Harmonic Helicity and Faraday Rotation in Gated Single-Layer 1T$'$-WTe$_2$

Signature of Molecular Orbital Symmetry in High-Order Harmonic Generation by Bichromatic Circularly Polarized Laser Pulses

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