title: Observation of phase-matched relativistic harmonic generation
abstract: Phase-matched relativistic harmonic generation in plasmas is observed for the first time. Third-harmonic light is detected and discriminated spectrally and angularly from the harmonics generated from competing processes. Its angular pattern is a narrow forward-directed cone, which is consistent with phase matching of a high-order transverse mode in a plasma. The signal level is found to be on the same order of magnitude for a circularly polarized pump pulse as for a linearly polarized pump pulse.
authors.affiliation: Center for Ultrafast Optical Science, University of Michigan, Ann Arbor, Michigan 48109, USA.
authors.initials: S
authors.lastname: Chen
authors.initials: A
authors.lastname: Maksimchuk
authors.initials: E
authors.lastname: Esarey
authors.initials: D
authors.lastname: Umstadter