Adiabatic population inversion in I2 vapor with picosecond laser pulses

Melinger, Joseph S.; Hariharan, A.; Gandhi, Suketu R.; Warren, W. S.

doi:10.1063/1.460971

Cited by 106 publications

(50 citation statements)

References 26 publications

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“…The globally optimal solution in the weak response regime comes naturally as the initial input to start the iterative solutions in the strong response regime. The use of chirped pulses in the strong response regime has proved useful both theoretically [44][45][46] and experimentally 47,48 in the control of population inversion in multilevel molecular and atomic systems or in the dissipative medium. The effect of chirp is related to the adiabatic passage of the material population dynamics via intensive fields in order to achieve an effective pulse.…”

Section: Discussionmentioning

confidence: 99%

Pump-dump control and the related transient absorption spectroscopies

Shen

Yan

Cheng

et al. 1999

The Journal of Chemical Physics

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We combine theories of optimal pump-dump control and the related transient probe absorption spectroscopy in order to elucidate the relation between these two optical processes and the possibility of experimental realization. In the weak response regime, we identify the globally optimal pair of pump-dump control fields, and further propose a second-order difference detection scheme to monitor the wave packets dynamics that is jointly controlled by both the pump and dump fields. The globally optimal solution serves also as the initial input for the iterative search for the optimal control fields in the strong response regime. We use a model I 2 molecule to demonstrate numerically the pump-dump control and the detection of a highly vibrationally excited wave packet focusing dynamics on the ground X surface in both the weak and strong response regimes. The I 2 B surface serves as the intermediate to assist the pump-dump control and the optical detection processes. Demonstrated in the strong response regime are the optimal pair of pump-dump molecular-pulses that invert nearly total population onto the predefined target region within a half period of vibration motion.

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Section: Discussionmentioning

confidence: 99%

Pump-dump control and the related transient absorption spectroscopies

Shen

Yan

Cheng

et al. 1999

The Journal of Chemical Physics

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“…Indeed, it was shown that picosecond frequency-swept laser pulses produce more selective excitation and better population transfer than transform-limited pulses with the same bandwidth, duo to the mechanism of population inversion by adiabatic sweeping [21,22,23,24].…”

Section: Introductionmentioning

confidence: 99%

Optimizing the photoassociation of cold atoms by use of chirped laser pulses

2004

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Abstract. Photoassociation of ultracold atoms induced by chirped picosecond pulses is analyzed in a nonperturbative treatment by following the wavepackets dynamics on the ground and excited surfaces. The initial state is described by a Boltzmann distribution of continuum scattering states. The chosen example is photoassociation of cesium atoms at temperature T=54 µK from the a 3 Σ + u (6s, 6s) continuum to bound levels in the external well of the 0 − g (6s + 6p 3/2 ) potential. We study how the modification of the pulse characteristics (carrier frequency, duration, linear chirp rate and intensity) can enhance the number of photoassociated molecules and suggest ways of optimizing the production of stable molecules.

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“…For example total population transfer has been achieved via multilevel ladder climbing [4][5][6][7][8][9] and Stimulated Raman Adiabatic Passage [10].…”

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confidence: 99%

Observation of Coherent Transients in Ultrashort Chirped Excitation of an Undamped Two-Level System

et al. 2001

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The effects of Coherent excitation of a two level system with a linearly chirped pulse are studied theoretically and experimentally (in Rb (5s -5p)) in the low field regime. The Coherent Transients are measured directly on the excited state population on an ultrashort time scale. A sharp step corresponds to the passage through resonance. It is followed by oscillations resulting from interferences between off-resonant and resonant contributions. We finally show the equivalence between this experiment and Fresnel diffraction by a sharp edge.Coherent excitation of atomic transitions is a general phenomenon occurring whenever electromagnetic radiation interacts with atoms. This interaction may result in various kinds of processes, for example Rabi oscillations, free induction decay, adiabatic population transfer and Coherent Transients (CT) [1]. By simply varying the temporal shape of the pulses, a great variety of systems can be manipulated such as spins in Nuclear Magnetic Resonance [2] or atomic and molecular systems in coherent control schemes [3]. We consider here the simplest case of linearly chirped pulses where the "instantaneous frequency" drifts in time.Depending on the frequency sweep and on the intensity, adiabatic following can be observed with a significant population transfer. For example total population transfer has been achieved via multilevel ladder climbing [4][5][6][7][8][9] and Stimulated Raman Adiabatic Passage [10].On the contrary if the adiabaticity criterion is not fulfilled, the final population depends crucially on the pulse integral and CT dominate the interaction. This letter presents theoretical and experimental studies of these Coherent Transients. Although many works have dealt with the transfer efficiency into the final state, we report here the first direct observation of these transients on a subpicosecond time scale. The CT result in oscillating population. This is a signature of interferences between resonant and non-resonant excitation. A detailed understanding of this behaviour is crucial to analyze pumpprobe experiments in which dynamics takes place on the same time scale as laser interaction. Due to the difficulty to control properly the laser pulses, the effects of CT are most often ignored [11].Similarities can be found with optical CT observed in the experiments of free induction decay or photon echoes which provide relaxation rates [12][13][14]. In these experiments, they observed on the transmitted optical signal, a beat between initially induced polarisation of the medium at resonance and a near-resonant laser. In the particular case of a single chirped optical pulse, the beat frequency increases linearly after passage through resonance, following the increase of resonance mismatch [15]. On the contrary to these previous studies, the present report involves CT directly observed on the population before relaxation becomes significant. The beats result here from interferences between the resonant and non-resonance excitation paths. The passage through resonance does not ...

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Adiabatic population inversion in I2 vapor with picosecond laser pulses

Cited by 106 publications

References 26 publications

Pump-dump control and the related transient absorption spectroscopies

Pump-dump control and the related transient absorption spectroscopies

Optimizing the photoassociation of cold atoms by use of chirped laser pulses

Observation of Coherent Transients in Ultrashort Chirped Excitation of an Undamped Two-Level System

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