Femtosecond pulse shaping

Baumert, T., Brixner, T., SeyMed, V., Strehle, M., and Gerber, G. 1997. Femtosecond pulse shaping by an evolutionary algorithm with feedback. Appl. Phys. B-Lasers Opt. 65 (6) 779-82. 

Frumker, E., and Silberberg, Y. 2007. Femtosecond pulse shaping using a two-dimensional liquid-crystal spatial hght modulator. Opt. Lett. 32 1384—86. 

Weiner, A. M. 2000. Femtosecond pulse shaping using spatial light modulators. Rev. Sci. Instrum. 71(5) 1929-60. 

As mentioned in the introduction, the ability to shape femtosecond laser pulses with unprecedented precision is the key to efficient control of photophysical and photochemical processes at the quantum level. In this section, we present the fundamentals of femtosecond pulse shaping and introduce specific pulse shapes that are used in the experiments and simulations presented in the following sections. We start with the electric field of a bandwidth-limited (BWL) femtosecond laser pulse written in terms of its positive frequency analytic signal... 

Advances in the theory and implementation of femtosecond pulse shaping have spurred a revolution in the coherent control of atomic and molecular processes. By creating complex vibrational and/or electronic wavefunctions with tailored pulses, it is now possible to guide many chemical and physical processes such as... 

Further advances in the field of coherent chemistry will require improved time resolution and tunability of the laser sources in the experiments [434]. Shorter laser pulses with a pulse duration of less than 20 fs will be appropriate. The optimum control technique will be achieved by specially tailored femtosecond pulse shapes [435-439], determined by sophisticated calculations using the theories of coherent chemistry [440-444]. Finally, more elaborate polarization and multipulse excitation schemes, including chirped and ultra-short pulses, will be needed. 

B. Kohler, J.L. Krause, F. Raski, C. Rose-Petruck, R.M. Whitnett, K.R. Wilson, V.V. Yakovlev, and Y.J. Yan, Femtosecond Pulse Shaping for Molecular Control in Femtosecond Reaction Dynamics, D.A. Wiersma (ed.) (North-HoIIand, Amsterdam, 1994), p 209. 

The fact that such an experimental window for coherent control in liquids does actually exist was verified in experiments on the selective multiphoton excitation of two distinct electronically and structurally complex dye molecules in solution (Brixner et al. 2001(b)). In these experiments, despite the failure of single-parameter variation (wavelength, intensity or linear chirp control), adaptive femtosecond pulse shaping revealed that complex laser fields could achieve chemically selective molecular excitation. These results prove, first, that the phase coherence of complex molecules persists for more than 100 fs in a solvent environment. Second, this is direct proof that it is the nontrivial coherent manipulation of the excited state and not of the frequency-dependent two-photon cross sections that is responsible for the coherent control of the population of the excited molecular state. 

Kawashima, H., M. M. Wefers, et al. (1995). Femtosecond pulse shaping, multiple-pulse spectroscopy, and optical control. Ann. Rev. Phys. Chem. 46, 627. 

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