Recurring Molecular Alignment Induced by Pulsed Nonresonant Laser Fields

2001 ◽  
Vol 66 (7) ◽  
pp. 991-1004 ◽  
Author(s):  
Long Cai ◽  
Břetislav Friedrich
Keyword(s):  
Laser Pulse ◽  
Laser Field ◽  
Analytic Solution ◽  
Short Pulse ◽  
Molecular Alignment ◽  
Time Dependent ◽  
Molecular Axis ◽  
Linear Molecule ◽  
Numerical Computations ◽  
Laser Fields

We examine the rotational wavepackets created by the nonadiabatic interaction of a linear molecule with a pulsed nonresonant laser field. We map out the recurrences of the wavepackets and of the concomitant alignment as a function of the duration and intensity of the laser pulse. We derive an analytic solution to the time-dependent Schrödinger equation in the short-pulse limit and find it to agree quantitatively with our numerical computations. This indicates that the recurrences are favored under an impulsive transfer of action from the radiative field to the molecule. The recurring wavepackets afford field-free alignment of the molecular axis.

Photoelectron Imaging on Time-Dependent Molecular Alignment Created by a Femtosecond Laser Pulse

2001 ◽  
Vol 86 (20) ◽  
pp. 4500-4503 ◽  
Author(s):  
Masaaki Tsubouchi ◽  
Benjamin J. Whitaker ◽  
Li Wang ◽  
Hiroshi Kohguchi ◽  
Toshinori Suzuki
Keyword(s):  
Laser Pulse ◽  
Femtosecond Laser ◽  
Femtosecond Laser Pulse ◽  
Molecular Alignment ◽  
Time Dependent ◽  
Photoelectron Imaging

Bayesian approach for the optimal control of high-order harmonics for the generation of ultrashort attosecond laser pulses

2021 ◽  
Author(s):  
Wei-Teng Wang ◽  
Yae-Lin Sheu ◽  
Shih-I Chu
Keyword(s):  
Laser Pulse ◽  
Laser Field ◽  
Pseudospectral Method ◽  
Laser Pulses ◽  
Optimization Method ◽  
High Order ◽  
Time Dependent ◽  
Bayesian Optimization ◽  
Time Frequency ◽  
Isolated Attosecond Pulse

Abstract We present an efficient and powerful method to optimize the production of high-order harmonic generation (HHG) and ultrashort single attosecond laser pulses. The system under investigation is the helium atoms that are exposed to the combination of chirped two-color mid-IR laser field and its 34th harmonic. The time-dependent Schrödinger equation is solved accurately and efficiently by means of the time-dependent generalized pseudospectral method and the time-frequency spectrum is obtained by the wavelet transform. We extend the machine-learning based optimization method, called Bayesian optimization (BO), to optimize the incident laser pulse to generate ultrashort attosecond laser pulse successfully for the first time. It is shown that the intensity of HHG power spectrum from the plateau region to the cutoff is enhanced by the optimized laser field by several orders of magnitude. Further, an ultrafast isolated attosecond pulse of 10 attosecond can be generated efficiently by superposing the plateau harmonics.

The Instability of Molecules in Laser Field and Isotope Separation

1981 ◽  
Vol 36 (8) ◽  
pp. 813-818
Author(s):  
Ke-hsueh Li
Keyword(s):  
Differential Equation ◽  
Dipole Moment ◽  
Laser Pulse ◽  
Nonlinear Differential Equation ◽  
Laser Field ◽  
Isotope Separation ◽  
Schroedinger Equation ◽  
Time Dependent ◽  
Unimolecular Reaction ◽  
Raman Process

Abstract In the present paper the nonlinear differential equation describing the selective decomposition of a molecule as an unimolecular reaction has be deduced from the usual time dependent semi-classical Schroedinger Equation. The selective conditions for the instability of a molecule are discussed. The thresholds of the required laser intensities for ICl and HCl diatomic molecules are estimated respectively, where one type of isotope molecules ought to be decomposed for hundred per cent in a laser pulse for different pulse widths. And possibly selective decomposition of the molecule without permanent dipole moment by Raman process is also discussed briefly.

ENHANCEMENT AND EXTENSION OF HIGH-ORDER HARMONIC EMISSION AND AN ISOLATED SUB-100 AS PULSE GENERATION FROM TWO-COLOR LASER FIELDS

2010 ◽  
Vol 09 (04) ◽  
pp. 735-744 ◽  
Author(s):  
YA-HUI GUO ◽  
HAI-XIANG HE ◽  
JIAN-YONG LIU ◽  
GUO-ZHONG HE
Keyword(s):  
Laser Pulse ◽  
Delay Time ◽  
Laser Field ◽  
Extreme Ultraviolet ◽  
Pulse Generation ◽  
Laser Fields ◽  
High Order Harmonic ◽  
Fundamental Laser ◽  
Color Scheme ◽  
Selection Of

We theoretically propose a method to generate a coherent and ultrabroad extreme ultraviolet supercontinuum using Ar + ions. When the medium is exposed to a two-color laser field, which is synthesized by a few-cycle fundamental laser pulse and its second-harmonics pulse, the harmonics spectrum presents a two-plateau structure. For the selection of the short quantum path utilizing the two-color scheme, the supercontinuum in the second plateau is almost synchronously emitted and a single 58 attosecond (as) pulse can be directly obtained. By increasing the intensity of the controlling field or adjusting the delay time of the two laser fields, a more intense isolated as pulse will be generated.

scholarly journals On the Stark Effect of the O I 777-nm Triplet in Plasma and Laser Fields

Atoms ◽  
2020 ◽  
Vol 8 (4) ◽  
pp. 84
Author(s):  
Evgeny Stambulchik ◽  
Eyal Kroupp ◽  
Yitzhak Maron ◽  
Victor Malka
Keyword(s):  
Spectral Line ◽  
Density Matrix ◽  
Computer Simulations ◽  
Laser Field ◽  
Stark Effect ◽  
Time Dependent ◽  
Laser Fields ◽  
Resonant Laser ◽  
Triplet Transition ◽  
Dependent Density

The O I 777-nm triplet transition is often used for plasma density diagnostics. It is also employed in nonlinear optics setups for producing quasi-comb structures when pumped by a near-resonant laser field. Here, we apply computer simulations to situations of the radiating atom subjected to the plasma microfields, laser fields, and both perturbations together. Our results, in particular, resolve a controversy related to the spectral line anomalously broadened in some laser-produced plasmas. The importance of using time-dependent density matrix is discussed.

scholarly journals Laser Pulse Shortening via Zero-Dispersion Phase Matching of Parametric Raman Interactions in Crystals

Crystals ◽  
2020 ◽  
Vol 11 (1) ◽  
pp. 19
Author(s):  
Sergei N. Smetanin ◽  
Michal Jelínek ◽  
Dmitry P. Tereshchenko ◽  
Mikhail N. Ershkov ◽  
Václav Kubeček
Keyword(s):  
Laser Pulse ◽  
Short Pulse ◽  
Matching Condition ◽  
Phase Matching ◽  
Dispersion Phase ◽  
Birefringent Crystal ◽  
Raman Lasers ◽  
Birefringent Crystals ◽  
Phase Matching Condition ◽  
Ultra Short Pulse

We propose and study the conditions of zero-dispersion phase matching for parametric Raman interactions in birefringent crystals differing by anisotropy of zero-dispersion wavelength and allowing for the spectral tuning of the zero-dispersion phase-matching condition. We choose a highly birefringent crystal of calcite having a wide zero-dispersion anisotropy range for the demonstration of new effects of laser pulse shortening in parametric Raman lasers with spectrally tunable zero-dispersion phase matching. We demonstrate the anti-Stokes (1168 nm) and multi-Stokes (1629 nm) picosecond pulse shortening and self-separation of single 80-ps ultra-short pulse from the zero-dispersion phase-matched parametric Raman lasers that are based on the calcite crystal without using any electro-optical device.

The study of time dependent, broadband X-ray emission from ultra-short pulse laser produced plasmas

1994 ◽  
Author(s):  
Ronnie Shepherd ◽  
Rex Booth ◽  
Dwight Price ◽  
Rosemary Walling ◽  
Richard More ◽  
...  
Keyword(s):  
Pulse Laser ◽  
Short Pulse ◽  
Time Dependent ◽  
X Ray ◽  
Short Pulse Laser ◽  
Ultra Short Pulse ◽  
Ultra Short Pulse Laser
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