title: Phase Matching For Large-scale Frequency Upconversion in Plasma.
abstract: We consider phase matching in the generation of very short-wavelength coherent radiation by nonlinear frequency upconversion in plasma and suggest some ways to improve phase matching in high-order harmonic generation. We obtain what are to our knowledge the first simple analytical expressions for a phase-matching factor in multiphoton mixing of an arbitrary order and demonstrate theoretically that high-order difference-frequency mixing in plasma could be, owing to its potential for phase-matching optimization, a more promising method of large-scale frequency upconversion than high-order harmonic generation.
authors.forename: P L
authors.initials: PL
authors.lastname: Shkolnikov
authors.forename: A E
authors.initials: AE
authors.lastname: Kaplan
authors.forename: A
authors.initials: A
authors.lastname: Lago