title: Phase matching, quasi-phase matching, and pulse compression in a single waveguide for enhanced high-harmonic generation.
abstract: We demonstrate, for the first time to our knowledge, that the efficient region of high-harmonic generation can be shifted from lower to higher photon energies by combining phase matching, quasi-phase matching, and pulse compression in a single gas-filled waveguide. An intrawaveguide pulse compression process that works through a combination of ionization-induced refraction and guiding shortens the laser pulse as it propagates through an Ar-filled waveguide. This leads to enhanced harmonic emission at high photon energies near 95 eV while it reduces emission at low photon energies near 45 eV. The waveguide geometry also mitigates ionization-induced refraction, allowing Ar gas with high effective nonlinear susceptibility to be used.
authors.affiliation: JILA, Department of Physics, and National Science Foundation Engineering Research Center in Extreme Ultraviolet Science and Technology, University of Colorado at Boulder and National Institute of Standards and Technology, Boulder, Colorado 80309-0440, USA.
authors.forename: Xiaoshi
authors.initials: X
authors.lastname: Zhang
authors.forename: Amy
authors.initials: A
authors.lastname: Lytle
authors.forename: Tenio
authors.initials: T
authors.lastname: Popmintchev
authors.forename: Ariel
authors.initials: A
authors.lastname: Paul
authors.forename: Nick
authors.initials: N
authors.lastname: Wagner
authors.forename: Margaret
authors.initials: M
authors.lastname: Murnane
authors.forename: Henry
authors.initials: H
authors.lastname: Kapteyn