Elliptically Polarized High-Order Harmonic Emission from Molecules in Linearly Polarized Laser Fields

Zhou, Xibin; Lock, Robynne M.; Wagner, Nick; Li, Wen; Kapteyn, Henry C.; Murnane, Margaret M.

doi:10.1103/physrevlett.102.073902

Cited by 221 publications

(154 citation statements)

References 23 publications

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“…It has also been observed in N 2 that orbitals lying energetically below the HOMO, in particular the HOMO-1, also contribute to HHG in molecules [20]. Recent theoretical and experimental studies of the HHG polarization provide additional support for multiorbital effects [52][53][54]. The experimental phase determined for N 2 may have both HOMO and HOMO-1 contributions.…”

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confidence: 91%

High-order harmonic phase in molecular nitrogen

et al. 2009

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Electronic structure in atoms and molecules modulates the amplitude and phase of high harmonic generation (HHG). We report measurements of the high harmonic spectral amplitude and phase in N 2 . The phase is measured interferometrically by beating the N 2 harmonics with those of an Ar reference oscillator in a gas mixture. A rapid phase shift of 0.2π is observed in the vicinity of the HHG spectral minimum, where a shift of π had been presumed [J. Itatani et al., Nature 432, 867 (2004)]. We compare the phase measurements to a simulation of the HHG recombination step in N 2 that is based on a simple interference model. The results of the simulation suggest that modifications beyond the simple interference model are needed to explain HHG spectra in molecules.

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confidence: 91%

High-order harmonic phase in molecular nitrogen

et al. 2009

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“…Figure 2 presents then the evolution of the normalized intensity The ellipticity of each harmonic in the two-colour configuration is evaluated from equation (1), which will be derived below. First, the ellipticity can be expressed as follows 17 assuming that e is small, which is naturally correct at Brewster's angle:…”

Section: Methodsmentioning

confidence: 99%

“…Several methods were proposed to overcome this restriction [8][9][10][11][12][13][14][15][16] , but only three of them really show the production of high harmonics with elliptical polarization and non-negligible efficiency. The first possibility consists in generating harmonics in pre-aligned molecules [17][18][19] . In this approach, however, the measured ellipticity can hardly exceed 35% and only for harmonics corresponding to the low efficiency part of the generated spectrum.…”

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confidence: 99%

Towards enabling femtosecond helicity-dependent spectroscopy with high-harmonic sources

et al. 2015

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Recent advances in high-harmonic generation gave rise to soft X-ray pulses with higher intensity, shorter duration and higher photon energy. One of the remaining shortages of this source is its restriction to linear polarization, since the yield of generation of elliptically polarized high harmonics has been low so far. We here show how this limitation is overcome by using a cross-polarized two-colour laser field. With this simple technique, we reach high degrees of ellipticity (up to 75%) with efficiencies similar to classically generated linearly polarized harmonics. To demonstrate these features and to prove the capacity of our source for applications, we measure the X-ray magnetic circular dichroism (XMCD) effect of nickel at the M 2,3 absorption edge around 67 eV. There results open up the way towards femtosecond time-resolved experiments using high harmonics exploiting the powerful element-sensitive XMCD effect and resolving the ultrafast magnetization dynamics of individual components in complex materials.

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“…High-order harmonic radiation is coherent with welldefined polarization [14]. We can write the emitted radiation field E em (t) as…”

Section: Harmonic Polarizationmentioning

confidence: 99%

“…The direction of greatest emission corresponds to the main polarization direction, and the emission in the orthogonal direction is a measure for the ellipticity of the emitted radiation [14]. Only under considerable effort for the experimentalist, the harmonic phase can be measured interferometrically as a function of alignment angle [10,23] or as a function of harmonic order [24].…”

Section: Harmonic Polarizationmentioning

confidence: 99%

Two-center interference and ellipticity in high-order harmonic generation fromH2+

Zwan

Lein

2010

Phys. Rev. A

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We present a theoretical investigation into the two-center interference in aligned H + 2 . The influence of the laser field on the recombination step is investigated by comparing laser-induced harmonic generation with harmonic generation from field-free collisions of Gaussian wave packets with the core. We find that for different Gaussian wave packets colliding with the molecule, the interference minimum occurs at the same alignment angle. The same result is obtained for the laser-induced spectrum when only a single electronic trajectory per harmonic contributes. When multiple electronic trajectories contribute, we find an effect on the minimum position because the interference between short and long trajectories is alignment dependent. The two-center interference and the influence of the Coulombic potential are clearly seen not only in the harmonic intensity and phase but also in the polarization direction and ellipticity. We observe significant ellipticity of the emitted radiation around the two-center interference minimum.

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Elliptically Polarized High-Order Harmonic Emission from Molecules in Linearly Polarized Laser Fields

Cited by 221 publications

References 23 publications

High-order harmonic phase in molecular nitrogen

High-order harmonic phase in molecular nitrogen

Towards enabling femtosecond helicity-dependent spectroscopy with high-harmonic sources

Two-center interference and ellipticity in high-order harmonic generation fromH2+

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