Generation of high-order harmonics in a self-guided beam

Generation of high-order harmonics in Xe was studied in a static cell at high pump energies, 5 m focal length, and up to 14 cm interaction lengths. Self-guided propagation of the pulse was observed experimentally and confirmed by a three-dimensional model. Phase-matched generation was demonstrated in the self-guided beam, and the high energy and low divergence of the harmonic radiation were explained. Harmonic field calculations, in good agreement with experimental results, allow for the explanation of the higher-order harmonic generation dynamics in the self-guided region.