Abstract
The excitation of two-level atoms in a laser field comprising many equally spaced coupled laser modes corresponding to a coherent pulse train is examined. The atom-field interaction is analysed via the optical Bloch equations for a rotating wave. In the limit of weak excitation they can be solved analytically and the time-averaged atomic excitation turns out to be a linear superposition of the contributions from the individual laser modes. Thus excitation spectra simply reflect the mode structure of the laser spectrum. Excitation spectra for strong fields are obtained by numerical integration of the optical Bloch equations. They exhibit a saturation behaviour differing significantly from the well known single-mode case. The temporal evolution towards the steady state is calculated for several numerical examples to clarify the origin of this behavior. For achieving maximum excitation, the laser pulse area, as in the single-pulse case, should be an odd multiple of π, and the mode spacing (pulse repetition rate) should exceed the natural linewidth of the atomic transition considerably. Under these conditions the time-averaged excited-state population approaches 1/2 while saturation broadening ensures nearly frequency-independent excitation within an extended fraction of the laser bandwidth.
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References
Loudon, R.: The quantum theory of light, 2nd edn. Oxford: Clarendon Press 1983
Allen, L., Eberly, J.H.: Optical resonance and two-level atoms. New York: Wiley 1975
Fontana, P.R.: Atomic radiative processes. New York: Academic Press 1982
Shore, B.W.: The theory of coherent atomic excitation. New York: Wiley 1990
Citron, M.L., Gray, H.R., Gabel, C.W., Stroud, C.R., Jr.: Phys. Rev. A16, 1507 (1977)
Feneuille, S., Schweighofer, M.-G., Oliver, G.: J. Phys. B9, 2003 (1976)
Armstrong, L., Jr., Feneuille, S.: J. Phys. B8, 546 (1975)
Mittleman, M.H.: Phys. Rev. A32, 276 (1985)
Bradley, L.C.: J. Opt. Soc. Am. B9, 1931 (1992)
Milonni, P.W., Thode, L.E.: Appl. Opt.31, 785 (1992)
Temkin, R.J.: J. Opt. Soc. Am. B10, 830 (1993)
Krüger, E.: Thesis, Universität Münster 1992
Strohmeier, P., Kersebom, T., Krüger, E., Nölle, H., Steuter, B., Schmand, J., Andrä, J.: Opt. Commun.73, 451 (1989)
Strohmeier, P., Horn, A., Kersebom, T., Schmand, J.: Z. Phys. D21, 215 (1991)
Grove, R.E., Wu, F.Y., Ezekiel, S.: Phys. Rev. A15, 227 (1977)
Herrmann, J., Wilhelmi, B.: Lasers for ultrashort light pulses. Berlin: Akademie-Verlag 1987
Rush, D.J., Ho, P.-T., Burdge, G.L.: Opt. Commun.52, 41 (1984)
Linde, D. von der: Appl. Phys. B39, 201 (1986)
Kluge, J., Wiechert, D., Linde, D. von der: Opt. Commun.51, 271 (1984)
Kane, D.M., Bramwell, S.R., Ferguson, A.I.: Appl. Phys. B39, 171 (1986)
Sommerfeld, A.: Vorlesungen über theoretische Physik. III: Elektrodynamik, 4th edn. Thun: Verlag Deutsch 1977
Bloch, F., Siegert, A.: Phys. Rev.57, 522 (1940)
Gibbs, H.M.: Phys. Rev. A8, 446 (1973)
Golub, J.E., Bai, Y.S., Mossberg, T.W.: Phys. Rev. A37, 119 (1988)
Genack, A.Z., Brewer, R.G.: Phys. Rev. A17, 1463 (1978)
DeVoe, R.G., Brewer, R.G.: Phys. Rev. A20, 2449 (1979)
Camparo, J.C., Frueholz, R.P.: Phys. Rev. A38, 6143 (1988)
Landau, L.D., Lifschitz, E.M.: Lehrbuch der theoretischen Physik. III: Quantenmechanik, 6th edn. Berlin: Akademie-Verlag 1979
Orriols, G.: Nuovo Cimento B53, 1 (1979)
Gaupp, A., Kuske, P., Andrä, H.J.: Phys. Rev. A26, 3351 (1982)
Nölle, B., Nölle, H., Schmand, J., Andrä, H.J.: Verh. Dtsch. Phys. Ges. (VI)27, 1260 (1992)
Moi, L.: Opt. Commun.50, 349 (1984)
Liang, J., Moi, L., Fabre, C.: Opt. Commun.52, 131 (1984)
Liang, J., Fabre, C.: Opt. Commun.59, 31 (1986)
Bülo, K.-H.: Thesis, Universität Münster 1988
Krüger, E.: (submitted to J. Opt. Soc. Am. B)