title: Grating-assisted phase matching in extreme nonlinear optics.
abstract: We propose a new technique for phase matching high harmonic generation that can be used for generating bright, tabletop, tunable, and coherent x-ray sources at keV photon energies. A weak quasi-cw counterpropagating field induces a sinusoidal modulation in the phase of the emitted harmonics that can be used for correcting the large plasma-induced phase mismatch. We develop an analytical model that describes this grating-assisted x-ray phase matching and predicts that very modest intensities (<10(10) W/cm2) of quasi-cw counterpropagating fields are required for implementation.
authors.affiliation: Department of Physics and JILA, University of Colorado at Boulder and NIST, Boulder, Colorado 80309, USA. oren.cohen@colorado.edu
authors.forename: Oren
authors.initials: O
authors.lastname: Cohen
authors.forename: Xiaoshi
authors.initials: X
authors.lastname: Zhang
authors.forename: Amy L
authors.initials: AL
authors.lastname: Lytle
authors.forename: Tenio
authors.initials: T
authors.lastname: Popmintchev
authors.forename: Margaret M
authors.initials: MM
authors.lastname: Murnane
authors.forename: Henry C
authors.initials: HC
authors.lastname: Kapteyn