title: Interaction-induced nonlinear refractive-index reduction of gases in the midinfrared regime.
abstract: The nonlinear optical response of a dilute atomic gas to ultrashort high-intensity midinfrared pulse excitation is calculated fully microscopically. The optically induced polarization dynamics is evaluated for the interacting many-electron system in a gas of hydrogen atoms. It is shown that the many-body effects during the excitation distinctly influence not only the atomic ionization dynamics, but also the nonlinear polarization response in the midinfrared regime. The delicate balance between the Kerr focusing and the ionization-induced defocusing is dramatically modified and a significant decrease of the nonlinear refractive index is predicted for increasing wavelength of the exciting pulse.
authors: Arizona Center for Mathematical Sciences, Department of Mathematics, University of Arizona, Tucson, Arizona 85721, USA and College of Optical Sciences, University of Arizona, Tucson, Arizona 85721, USA.
authors: K
authors: K
authors: Schuh
authors: Arizona Center for Mathematical Sciences, Department of Mathematics, University of Arizona, Tucson, Arizona 85721, USA and College of Optical Sciences, University of Arizona, Tucson, Arizona 85721, USA.
authors: J V
authors: JV
authors: Moloney
authors: College of Optical Sciences, University of Arizona, Tucson, Arizona 85721, USA and Department of Physics and Material Science Center, Philipps-University, 35032 Marburg, Germany.
authors: S W
authors: SW
authors: Koch