title: Coherent amplification of an ultrashort pulse in a high- and swept-gain medium with level degeneracy.
abstract: A one-dimensional model of the coherent amplification in a high- and swept-gain amplifier in the presence of strong spontaneous emission is presented and applied to seeding an x-ray laser with a high harmonic pulse. The atomic structure of the amplifying medium includes level degeneracy, and the Maxwell-Bloch equations are used to describe the propagation and interaction processes. This analysis elucidates, in the most comprehensive way, the influence of the random spontaneous emission on the coherent amplification process, as reflected in the basic pulse parameters such as its shape, polarization, and coherence.
authors.affiliation: Center for Femto-Atto Science and Technology, and Advanced Photonics Research Institute, Gwangju Institute of Science and Technology, Gwangju 500-712, Korea.
authors.forename: Chul Min
authors.initials: CM
authors.lastname: Kim
authors.forename: Jongmin
authors.initials: J
authors.lastname: Lee
authors.forename: Karol A
authors.initials: KA
authors.lastname: Janulewicz