Space-time coupling in femtosecond pulse shaping and its effects on coherent control

Institute of Applied Physics, University of Bern, Sidlerstrasse 5, CH-3012 Bern, Switzerland.
The Journal of Chemical Physics (Impact Factor: 2.95). 02/2009; 130(3):034302. DOI: 10.1063/1.3058478
Source: PubMed


We present a Fourier optical analysis of a typical femtosecond pulse shaping apparatus and derive analytic expressions for the space-time dependence of the emerging waveform after the pulse shaper and in the focal volume of an additional focusing element. For both geometries the results are verified experimentally. Hereafter, we analyze the influence of space-time coupling on nonlinear processes, specifically second harmonic generation, resonant interaction with an atomic three-level system, and resonant excitation of a diatomic molecule.

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    • "If, on the other hand, both pulses are superimposed in time, the instantaneous polarization of the excitation field varies as a function of the time delay. By using such polarization-shaped laser pulses [35] [36] [37] [38], it is possible to control and visualize a coherent process of alternating routing by scanning the temporal overlap stepwise and recording the spatial map of timeintegrated sample emission for each step. As seen in Fig. 5(e), the spatial contrast remains constant with decreasing temporal separation of the excitation pulses as long as both pulses are not superimposed in time. "
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    • "Thus, sensitivity is directly linked to the ability to control precisely the optical mode, and in the present case to the quality of pulse shaping. Although conventional pulse shaping technologies, e.g. using a programmable spatial light modulator inserted in a zero-dispersion line [10] [11] [12], allow for versatile and accurate shaping, they suffer from spatio-temporal effects [13] which would induce reduced visibility with the optimal mode and thus reduced sensitivity. "
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    • "These studies have more recently been extended to the focal volume after a lens [17] [18]. "
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