Abstract
We use counterpropagating light to directly observe the coherent buildup of high harmonic generation in a hollow waveguide geometry. We measure, for the first time, coherence lengths for high photon energies that cannot be phase matched using conventional approaches. We also probe the transition through phase matching, the ionization level at which different harmonic orders are generated, and the change in the coherence length as the driving laser is depleted. These results directly prescribe the optimal structures or pulse trains required for implementing quasiphase matching.
Original language | English |
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Article number | 123904 |
Journal | Physical Review Letters |
Volume | 98 |
Issue number | 12 |
DOIs | |
State | Published - 23 Mar 2007 |
Externally published | Yes |