Efficient Excitation and Control of Atomic Systems with Unipolar Half-Cycle XUV Attosecond Pulses

2019 ◽  
Author(s):  
R. M. Arkhipov ◽  
A. V. Pakhomov ◽  
M. V. Arkhipov ◽  
I. Babushkin ◽  
A. Demircan ◽  
...  
Keyword(s):  
Half Cycle ◽  
Atomic Systems ◽  
Attosecond Pulses ◽  
And Control

scholarly journals Control of the polarization direction of isolated attosecond pulses using inhomogeneous two-color fields

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Stephen Maina Njoroge ◽  
Hua Yuan ◽  
Kinyua Dickson ◽  
Qingbin Zhang ◽  
Pengfei Lan
Keyword(s):  
Polarization Direction ◽  
Relative Angle ◽  
Water Window ◽  
High Order Harmonic ◽  
Fundamental Pulse ◽  
Wide Range ◽  
Attosecond Pulses ◽  
Linearly Polarized ◽  
Window Region ◽  
And Control

AbstractWe theoretically demonstrate the control of the polarization direction of isolated attosecond pulses (IAPs) with inhomogeneous two-color fields synthesized by an 800-nm fundamental pulse and a 2000-nm control pulse having crossed linear polarizations. The results show that by using the temporally and spatially shaped field, the high-order harmonic generation (HHG) process can be efficiently controlled. An ultra-broad supercontinuum ranging from 150th to 400th harmonics which covers the water window region is generated. Such a supercontinuum supports the generation of a 64-as linearly polarized IAP, whose polarization direction is at about 45° with respect to the x axis. Moreover, we analyze the influence of the inhomogeneity parameters and the relative angle of the fundamental and control pulses on the IAP generation. It is shown that the polarization direction of the IAP can rotate in a wide range approximately from 8° to 90° relative to the x axis when the inhomogeneity parameters and the relative angle vary.

Experimental Verification of Circuit Analog of Three- and Four-Level Electromagnetically Induced Transparency

2011 ◽  
Vol 415-417 ◽  
pp. 1340-1349 ◽  
Author(s):  
Xi Chen ◽  
Xia Min Leng ◽  
Jing Xin Li ◽  
Yi Tsen Yeh ◽  
Teh Chau Liau ◽  
...  
Keyword(s):  
Quantum Interference ◽  
Electromagnetically Induced Transparency ◽  
External Control ◽  
Atomic Systems ◽  
Classical Counterpart ◽  
Atomic Vapors ◽  
Capacitor Coupling ◽  
Atom Interaction ◽  
And Control ◽  
Induced Transparency

Since a two-level resonant atomic system can be simulated by a simple circuit, three- and four-level electromagnetically induced transparency (EIT) that occur due to light-atom interaction can find its classical counterpart in circuit analog. As the optical response of an EIT atomic medium (including atomic vapors and semiconductor-quantum-dot dielectrics) can be controlled via tunable quantum interference induced by applied external control fields, in the scheme of circuit analog, such a controllable manipulation is achieved via capacitor coupling, where two loops are coupled by a capacitor that can represent the applied control fields in atomic EIT. Both numerical simulation and experimental demonstration of three- and four-level EIT were performed based on such a scenario of circuit analog. The classical “coherence” relevant to quantum interference among transitions pathways driven by both probe and control fields in EIT atomic systems has been manifested in the present circuit analog of EIT.

Generation of the high-intensity single harmonic energy peak and attosecond pulse by using resonance ionization schemes from atoms and molecules

2020 ◽  
pp. 2150022
Author(s):  
Xiaodan Jing ◽  
Liqiang Feng ◽  
Li Liu ◽  
John Mccain ◽  
Yi Li
Keyword(s):  
Molecular System ◽  
Attosecond Pulse ◽  
Resonance Ionization ◽  
Half Cycle ◽  
Harmonic Intensity ◽  
Molecular Systems ◽  
Unipolar Pulse ◽  
Energy Peak ◽  
Attosecond Pulses ◽  
Time Region

The lower harmonic intensity is still the reason that limits the application of attosecond pulse. Thus, in this paper, on the basis of resonance ionization schemes, we propose the effective methods to improve the harmonic intensity of atomic and molecular systems. For atomic system (i.e. He atom), with the combination of chirped-UV pulse, not only the harmonic cutoff can be extended, but also the harmonic intensity can be enhanced, caused by the UV resonance ionization between ground state and excited state. As a result, the single harmonic energy peak (HEP) with the higher intensity and higher emitted photon energy can be obtained, which can support the attosecond pulses shorter than 40 as. For the molecular system (i.e. [Formula: see text] and [Formula: see text]), by properly choosing the pulse duration of the fundamental pulse, the time region of charge resonance enhanced ionization (CREI) can be well controlled. Therefore, the maximum HEP with the higher intensity can be obtained. Second, by properly adding a half-cycle unipolar pulse, the selected maximum HEP in the CREI region can be further extended. Thus, an intense and broad spectral region can be produced, which can generate the attosecond pulses with durations of 36[Formula: see text]as.

Half-cycle Cutoffs up to the Oxygen K-edge: Signatures of Isolated Attosecond Pulses Across the Water Window

CLEO: 2014 ◽  
2014 ◽  
Author(s):  
Francisco Silva ◽  
Stephan M. Teichmann ◽  
Seth L. Cousin ◽  
Michael Hemmer ◽  
Jens Biegert
Keyword(s):  
Half Cycle ◽  
Water Window ◽  
Attosecond Pulses

Control of the half-cycle harmonic emission process for generating the intense and ultrashort single attosecond pulses (SAPs)

2020 ◽  
Vol 75 (11) ◽  
pp. 903-911
Author(s):  
Li-Qiang Feng ◽  
Li Liu
Keyword(s):  
Resonance Ionization ◽  
Half Cycle ◽  
Generation Process ◽  
Harmonic Intensity ◽  
Emission Process ◽  
Chirped Pulse ◽  
Attosecond Pulses ◽  
Higher Harmonic ◽  
Photon Resonance ◽  
Positive Half

AbstractIn this paper, the half-cycle harmonic generation process has been controlled by using the asymmetric inhomogeneous chirped pulse combined with the ultraviolet (UV) pulse. It is found that by properly optimizing the chirps and chirp delays of the fundamental two-color pulse, the optimal negative and positive half-cycle laser profiles for the harmonic cutoff extension can be obtained. Further, with the introduction of the negative and positive inhomogeneous effect, respectively, the harmonic cutoff from the negative and positive half-cycle laser profiles can be further improved. Next, with the assistance of the UV pulse, the harmonic intensity can be enhanced due to the UV resonance ionization. Moreover, the single and double UV photon resonance ionizations are much better for generating the higher harmonic intensity. As a result, the stronger and broader harmonic plateaus with the larger harmonic cutoff can be obtained, which can support the generation of the high-intensity ultrashort attosecond pulses with the pulse durations of sub-45 as.

scholarly journals Radially polarized, half-cycle, attosecond pulses from laser wakefields through coherent synchrotronlike radiation

2014 ◽  
Vol 90 (4) ◽  
Author(s):  
F. Y. Li ◽  
Z. M. Sheng ◽  
M. Chen ◽  
L. L. Yu ◽  
J. Meyer-ter-Vehn ◽  
...  
Keyword(s):  
Half Cycle ◽  
Attosecond Pulses ◽  
Radially Polarized

scholarly journals Giant half-cycle attosecond pulses

2012 ◽  
Vol 6 (5) ◽  
pp. 304-307 ◽  
Author(s):  
H.-C. Wu ◽  
J. Meyer-ter-Vehn
Keyword(s):  
Half Cycle ◽  
Attosecond Pulses

Waveform control in generations of intense water window attosecond pulses via multi-color combined field

2019 ◽  
Vol 33 (13) ◽  
pp. 1950130 ◽  
Author(s):  
Liang Li ◽  
Mian Zheng ◽  
R. Liqiang Feng ◽  
Yan Qiao
Keyword(s):  
Half Cycle ◽  
High Order Harmonic Generation ◽  
Initial State ◽  
Water Window ◽  
The Third ◽  
High Order Harmonic ◽  
Waveform Control ◽  
Attosecond Pulses ◽  
Color Field ◽  
Selective Enhancement

The waveform control in the improvements of high-order harmonic generation (HHG) spectra and attosecond pulse signals driven by the two-color and three-color combined fields has been theoretically investigated. (a) The results show that by properly controlling the [Formula: see text]–2[Formula: see text] two-color laser beam (including the modulations of chirps, carrier envelope phases and delay time), either the harmonic cutoff can be extended, showing a water window spectral continuum, or the selective enhancement of the single-order and two-order harmonics can be found. Further, with the introduction of a third controlling field, the efficiency of spectral continuum can be enhanced by two orders of magnitude compared with that from the two-color field. Moreover, the enhancement of HHG is not very sensitive to the frequency of the third field (i.e., the frequency of the third field is chosen to be 3[Formula: see text], 4[Formula: see text] and 6[Formula: see text]). Thus, some water window attosecond pulses with the durations of 60 as can be obtained. (b) Furthermore, the harmonic cutoff can be further extended when using a half-cycle controlling pulse or introducing the inhomogeneous effect of the laser field. Moreover, the efficiency of HHG can be further improved when the initial state is prepared as the superposition state of the ground state and some excited state of He atom. Consequently, a much broader spectral continuum with an intensity enhancement of another two orders of magnitude can be found. Finally, through the Fourier transformation of some spectral continuum, the intense water window attosecond pulses with the durations of 60 as can be produced.

scholarly journals Terawatt-scale optical half-cycle attosecond pulses

2018 ◽  
Vol 8 (1) ◽  
Author(s):  
Jiancai Xu ◽  
Baifei Shen ◽  
Xiaomei Zhang ◽  
Yin Shi ◽  
Liangliang Ji ◽  
...  
Keyword(s):  
Half Cycle ◽  
Attosecond Pulses
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