CONTROLLING THE ROTATIONAL DYNAMICS OF THE MOLECULAR ORIENTATION BY TWO TIME-DELAYED LASER PULSES

2011 ◽  
Vol 20 (03) ◽  
pp. 341-350 ◽  
Author(s):  
SHUWU XU ◽  
YUNXIA HUANG ◽  
XIANMING JI
Keyword(s):  
Time Delay ◽  
Molecular Orientation ◽  
Fourier Transforms ◽  
Transition Probability ◽  
Laser Pulses ◽  
Time Dependent ◽  
Rotational Period ◽  
Raman Transition ◽  
Relative Time ◽  
Rotational States

We show that the Raman transition probability can be manipulated by the relative time delay, the intensity ratio and the carrier-envelope phase between two time-delayed dual-color laser pulses. Our results indicate that when the second laser pulse is applied at half of the molecular rotational period, the contributions of the odd and the even rotational states are different. However, the two contributions are the same when the relative time delay is a full molecular rotational period. Time-dependent molecular orientation signals and their corresponding Fourier transforms validate the results.

NON-RESONANT TWO-PHOTON ABSORPTION CONTROL BY TWO TIME-DELAYED LASER PULSES

2013 ◽  
Vol 22 (01) ◽  
pp. 1350008 ◽  
Author(s):  
CHENHUI LU ◽  
SHIAN ZHANG ◽  
TIANQING JIA ◽  
JIANRONG QIU ◽  
ZHENRONG SUN
Keyword(s):  
Time Delay ◽  
Excited States ◽  
Molecular System ◽  
Transition Probability ◽  
Laser Pulses ◽  
Photon Absorption ◽  
Two Photon Absorption ◽  
Carrier Envelope Phase ◽  
Two Photon ◽  
Absorption Control

In this paper, we theoretically investigate the control of the non-resonant two-photon absorption induced by two time-delayed laser pulses, and an analytical solution for the dependence of the two-photon transition probability on the time delay and relative carrier-envelope phase of the two laser pulses is achieved. We show that the two-photon absorption can be significantly enhanced or completely suppressed by varying the time delay between the two laser pulses or their relative carrier-envelope phase. We also show that the two-photon absorption can be selectively excited when two excited states are simultaneously excited. Furthermore, we discuss the two-photon absorption control in the molecular system and analyze the effect of the absorption bandwidth on the control efficiency of the two-photon absorption.

scholarly journals Dynamics of the Creation of a Rotating Bose–Einstein Condensation by Two Photon Raman Transition Using a Laguerre–Gaussian Laser Pulse

Atoms ◽  
2021 ◽  
Vol 9 (1) ◽  
pp. 14
Author(s):  
Koushik Mukherjee ◽  
Soumik Bandyopadhyay ◽  
Dilip Angom ◽  
Andrew M. Martin ◽  
Sonjoy Majumder
Keyword(s):  
Interaction Strength ◽  
Transition Process ◽  
Laser Pulses ◽  
Harmonic Trap ◽  
Einstein Condensation ◽  
Raman Transition ◽  
Two Photon ◽  
Final Population ◽  
The Creation ◽  
Bose Einstein

We present numerical simulations to unravel the dynamics associated with the creation of a vortex in a Bose–Einstein condensate (BEC), from another nonrotating BEC using two-photon Raman transition with Gaussian (G) and Laguerre–Gaussian (LG) laser pulses. In particular, we consider BEC of Rb atoms at their hyperfine ground states confined in a quasi two dimensional harmonic trap. Optical dipole potentials created by G and LG laser pulses modify the harmonic trap in such a way that density patterns of the condensates during the Raman transition process depend on the sign of the generated vortex. We investigate the role played by the Raman coupling parameter manifested through dimensionless peak Rabi frequency and intercomponent interaction on the dynamics during the population transfer process and on the final population of the rotating condensate. During the Raman transition process, the two BECs tend to have larger overlap with each other for stronger intercomponent interaction strength.

Nonlinear Phenomena in Axially Moving Beams with Speed-Dependent Tension and Tension-Dependent Speed

2021 ◽  
Vol 31 (03) ◽  
pp. 2150037
Author(s):  
Ling Chen ◽  
You-Qi Tang ◽  
Shuang Liu ◽  
Yuan Zhou ◽  
Xing-Guang Liu
Keyword(s):  
Differential Equations ◽  
Fourth Order ◽  
Fourier Transforms ◽  
Time Dependent ◽  
Nonlinear Phenomena ◽  
Maximum Lyapunov Exponent ◽  
Material Derivative ◽  
Domains Of Attraction ◽  
Moving Beam ◽  
Galerkin Truncation

This paper investigates some nonlinear dynamical behaviors about domains of attraction, bifurcations, and chaos in an axially accelerating viscoelastic beam under a time-dependent tension and a time-dependent speed. The axial speed and the axial tension are coupled to each other on the basis of a harmonic variation over constant initial values. The transverse motion of the moving beam is governed by nonlinear integro-partial-differential equations with the rheological model of the Kelvin–Voigt energy dissipation mechanism, in which the material derivative is applied to the viscoelastic constitutive relation. The fourth-order Galerkin truncation is employed to transform the governing equation to a set of nonlinear ordinary differential equations. The nonlinear phenomena of the system are numerically determined by applying the fourth-order Runge–Kutta algorithm. The tristable and bistable domains of attraction on the stable steady state solution with a three-to-one internal resonance are analyzed emphatically by means of the fourth-order Galerkin truncation and the differential quadrature method, respectively. The system parameters on the bifurcation diagrams and the maximum Lyapunov exponent diagram are demonstrated by some numerical results of the displacement and speed of the moving beam. Furthermore, chaotic motion is identified in the forms of time histories, phase-plane portraits, fast Fourier transforms, and Poincaré sections.

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