Abstract
Harmonics generated from the electronic transition among continuum states are studied by a quantum scattering theory. The analytical formulas of the harmonics generated in one- and two-color circularly polarized (CP) laser fields are obtained rigorously. The harmonic generation amplitude is described by a pair of phased generalized Bessel functions, by which the conservation relations of the spin angular momentum are derived in a solid base and in a straightforward way. It is found that, owing to the spin angular momentum conservation, high-order harmonics cannot be generated in the one-color CP fields, but can be generated in the bichromatic CP fields. To a given harmonic order, two generation channels exist: one generates right CP harmonic, while the other generates left CP harmonic. When the driving CP modes are of opposite helicity, the generated right CP harmonic is of the comparable strength to the left CP harmonic. When the driving CP modes are of same helicity, the harmonic with the same helicity as the driving fields is much stronger than that with the opposite helicity to the driving fields. The selection rules of harmonics are different in these two kinds of bichromatic CP driving fields.
Graphic Abstract
Figure depicts the calculated harmonic spectra generated from Ar atoms. For the counter-rotating driving fields, the harmonic spectra exhibit clear plateau and sharp cutoff structures, for both the right and left CP harmonics. The right CP harmonics are of 3n-1 series in order, while the left CP harmonics are of 3n+1 series in order. Generally, the right CP harmonics are stronger than the adjacent left CP harmonics. For the co-rotating driving fields, the harmonic rate decreases fast as the harmonic order increases, thus the plateau and the cutoff structures are not clear as their counterparts in the previous case, for both right CP and left CP harmonics. The harmonic spectra change continuously in order. Each harmonic order has its right CP and left CP components, but generally, the left CP components are much smaller than the right CP components. It is also clear that the harmonics generated from counter-rotating BCP fields are much stronger than that generated from co-rotating BCP fields.
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This manuscript has associated data in a data repository. [Authors’ comment: The associated data in this manuscript can be gotten from corresponding author.]
References
F. Krausz, M. Ivanov, Attosecond physics. Rev. Mod. Phys. 81, 163 (2009)
P.B. Corkum, Plasma perspective on strong-field multiphoton ionization. Phys. Rev. Lett. 71, 1994 (1993)
D.C. Yost, T.R. Schibli, J. Ye, J.L. Tate, J. Hostetter, M.B. Gaarde, K.J. Schafer, Vacuum-ultraviolet frequency combs from below-threshold harmonics. Nature Phys. 5, 815 (2009)
W.H. Xiong, J.W. Geng, J.Y. Tang, L.Y. Peng, Q.H. Gong, Mechanisms of below-threshold harmonic generation in atoms. Phys. Rev. Lett. 112, 233001 (2014)
B.C. Wang, Y.F. Zhang, P.F. Lan, C.Y. Zhai, M. Li, X.S. Zhu, J. Chen, P.X. Lu, C.D. Lin, Anomalous ellipticity dependence of the generation of near-threshold harmonics in noble gases. Phys. Rev. A 103, 053119 (2021)
P.C. Li, Y.L. Sheu, Shih-I Chu, Role of nuclear symmetry in below-threshold harmonic generation of molecules. Phys. Rev. A 101, 011401 (2020)
F. Brunel, Harmonic generation due to plasma effects in a gas undergoing multiphoton ionization in the high-intensity limit. J. Opt. Soc. Am. B 7, 521 (1990)
A. Fleischer, O. Kfir, T. Diskin, P. Sidorenko, O. Cohen, Spin angular momentum and tunable polarization in high-harmonic generation. Nature Photonics 8, 543 (2014)
K.M. Dorney, L. Rego, N.J. Brooks, J. San Roman, C.T. Liao, J.L. Ellis, D. Zusin, D.C. Gentry, Q.L. Nguyen, J.M. Shaw, A. Picon, L. Plaja, H.C. Kapteyn, M.M. Murnane, C. Hernandez-Garcia, Controlling the polarization and vortex charge of attosecond high-harmonic beams via simultaneous spin-orbit momentum conservation. Nature Photonics 13(2), 123–130 (2019)
K.M. Dorney, J.L. Ellis, C. Hernddez-Garcia, D.D. Hickstein, C.A. Mancuso, N. Brooks, T. Fan, G. Fan, D. Zusin, C. Gentry, P. Grychtol, H.C. Kapteyn, M.M. Murnane, Helicity-Selective Enhancement and Polarization Control of Attosecond High Harmonic Waveforms Driven by Bichromatic Circularly Polarized Laser Fields. Phys. Rev. Lett. 119, 063201 (2017)
S. Long, W. Becker, J.K. McIver, Model calculations of polarization-dependent two-color high-harmonic Generation. Phys. Rev. A 52, 2262 (1995)
T. He, Y. Zhang, J.J. Zhao, X. Wang, Z. Shen, Z. Jin, T.M. Yan, Y.H. Jiang, Third-order harmonic generation in a bichromatic elliptical laser field. Opt. Express 29, 21936 (2021)
J. Gao, F. Shen, J.G. Eden, Quantum electrodynamic treatment of harmonic generation in intense optical fields. Phys. Rev. Lett. 81, 1833 (1998)
Y. Su, K. Fang, J. Zhang, A shortcut to study angular momentum transfer of Harmonic generation in intense laser fields. Opt. Express 29, 22679 (2021)
D.-S. Guo, T. Aberg, Quantum electrodynamical approach to multiphoton ionization in the high-intensity field. J. Phys. A 21, 4577 (1988)
J. Zhang, W. Zhang, Z. Xu, X. Li, P. Fu, D.-S. Guo, R.R. Freeman, The calculation of photoelectron angular distributions with jet-like structure from scattering theory. J. Phys. B 35, 4809 (2002)
L. Bai, J. Zhang, X. Zhang, Z. Xu, Angular distributions of multiphoton detachment of H- in various infrared laser fields. Phys. Rev. A 74, 025402 (2006)
X. Hu, H.X. Wang, D.-S. Guo, Phased Bessel Functions. Can. J. Phys. 96, 963 (2008)
D.S. Guo, T. Åberg, B. Crasemann, Scattering theory of multiphoton ionization in strong fields. Phys. Rev. A 40, 4997 (1989)
Jingtao Zhang, Takashi Nakajima, Coulomb effects in photoionization of H atoms irradiated by intense laser fields. Phys. Rev. A 75, 043403 (2007)
H.R. Reiss, Effect of an intense electromagnetic field on a weakly bound system. Phys. Rev. A 22, 1786 (1980)
L. Gao, X. Li, P. Fu, R.R. Freeman, D.-S. Guo, Nonperturbative quantum electrodynamics theory of high-order harmonic generation. Phys. Rev. A 61, 063407 (2000)
R. Baer, D. Neuhauser, P.R. Ždanska, N. Moiseyev, Ionization and high-order harmonic generation in aligned benzene by a short intense circularly polarized laser pulse. Phys. Rev. A 68, 043406 (2003)
J. Zhang, S. Li, Z. Xu, Above-threshold ionization of xenon atoms in a bichromatic phase-controlled laser field of linear and circular polarizations. Phys. Rev. A 69, 053410 (2004)
Acknowledgements
This work is supported by Chinese National Natural Science Foundation under Grant No. 12074261 and No.11674231, and Shanghai Natural Science Foundation under Grant No. 20ZR1441600.
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JTZ and XHR discussed the theoretical method. Z wrote the manuscript. XHR performed the simulations.
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Zhang, J., Ren, X. Harmonics generated in circularly polarized laser fields: a study on spin angular momentum conservation. Eur. Phys. J. D 77, 17 (2023). https://doi.org/10.1140/epjd/s10053-023-00595-8
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DOI: https://doi.org/10.1140/epjd/s10053-023-00595-8