Quantum path control in the presence of a half-cycle pulse to generate isolated attosecond pulse

2016 ◽  
Vol 49 (3) ◽  
pp. 231-237
Author(s):  
Li-Qing Li ◽  
Chang-Long Xia ◽  
Xiang-Yang Miao
Keyword(s):  
Attosecond Pulse ◽  
Half Cycle ◽  
Path Control ◽  
Isolated Attosecond Pulse ◽  
Cycle Pulse

Control of high-order harmonics from H2+ and D2+ for producing intense single attosecond pulse

2020 ◽  
Vol 34 (17) ◽  
pp. 2050192
Author(s):  
Liqiang Feng ◽  
John Mccain
Keyword(s):  
Heavy Nucleus ◽  
Light Nucleus ◽  
Laser Intensity ◽  
Attosecond Pulse ◽  
High Order ◽  
Emission Peak ◽  
Half Cycle ◽  
Harmonic Emission ◽  
High Order Harmonic ◽  
Cycle Pulse

Generally, the intensities of molecular high-order harmonic spectra from [Formula: see text] and its isotope molecules are quite different due to the effect of nuclear signals. Thus, in this paper, we investigate the change law of harmonic spectra from [Formula: see text] and [Formula: see text] driven by different laser fields and try to find the optimal harmonic spectra for producing intense single attosecond pulses (SAPs). The results show that in lower laser intensity case, the harmonic yield follows as [Formula: see text]; while, in higher laser intensity case, the harmonic yield meets the condition of [Formula: see text]. Further, by using this change law of harmonic yield and choosing the optimal harmonic emission peak (HEP), we can obtain the intense spectral continuum with the assistance of the half-cycle pulse (HCP). Next, with the superposition of some harmonics on the spectral continuum, the intense SAPs shorter than 37 as can be obtained from [Formula: see text] and [Formula: see text] harmonic spectra. Finally, the results show that the stronger attosecond signals can be obtained when the light nucleus or heavy nucleus molecules are driven by lower or higher laser intensities, respectively.

scholarly journals Laser control on molecular harmonic emission and isolated attosecond pulse generation

2017 ◽  
Vol 95 (3) ◽  
pp. 310-316
Author(s):  
Hang Liu ◽  
Rick Feng
Keyword(s):  
Pulse Duration ◽  
Laser Intensity ◽  
Pulse Generation ◽  
Attosecond Pulse ◽  
Time Dependent ◽  
Half Cycle ◽  
Time Frequency ◽  
Harmonic Emission ◽  
Isolated Attosecond Pulse ◽  
Laser Control

Laser control on the generations of the molecular high-order harmonic generation (MHHG) and the isolated attosecond pulse (IAP) from H2+ have been theoretically investigated through solving the non-Bohn–Oppenheimer time-dependent Schrödinger equation. It is found that (i) in the middle laser intensity (i.e., I = 4.0 × 1014 W/cm2), the contribution from negative-H to the MHHG is higher than that from the positive-H. With the decrease (i.e., I = 2.0 × 1014 W/cm2) or the increase (i.e., I = 7.0 × 1014 W/cm2) in laser intensity, the asymmetric contributions from the two H nuclei to the MHHG are decreased. (ii) Pulse duration investigation shows that the distributions of the MHHG in two H nuclei present similar contributions as the pulse duration is enhanced. (iii) Laser phase investigation shows that when the laser phase is chosen from 0.0π to 0.6π and from 1.7π to 2.0π, the contribution from the negative-H plays the main role in MHHG. When the laser phase is chosen from 0.7π to 1.6π, the contribution from the positive-H to the MHHG is remarkably enhanced and becomes greater than that from the negative-H. The time–frequency analyses of the MHHG and the time-dependent wave function are shown to explain the harmonic emission process and the electron motion in H2+. (iv) With the introduction of one or two half-cycle controlling pulses, the cutoff and the intensity of the MHHG spectra can be controlled. Finally, by selecting the harmonics generated during a single harmonic emission event, an IAP with the full width at half maximum of 48 as can be produced.

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