TY - JOUR
AU - D. Yost
AU - Thomas Schibli
AU - Jun Ye
AU - Jennifer Tate
AU - James Hostetter
AU - Mette Gaarde
AU - K. Schafer
AB - Recent demonstrations of high-harmonic generation (HHG) at very high repetition frequencies (approx100 MHz) may allow for the revolutionary transfer of frequency combs to the vacuum-ultraviolet range. This advance necessitates unifying optical frequency-comb technology with strong-field atomic physics. Whereas strong-field studies of HHG have often focused on above-threshold harmonic generation (photon energy above the ionization potential), for vacuum-ultraviolet frequency combs an understanding of below-threshold harmonic orders and their generation process is crucial. Here, we present a new and quantitative study of the harmonics 7–13 generated below and near the ionization threshold in xenon gas with an intense 1,070 nm driving field. We show multiple generation pathways for these harmonics that are manifested as on-axis interference in the harmonic yield. This discovery provides a new understanding of the strong-field, below-threshold dynamics under the influence of an atomic potential and allows us to quantitatively assess the achievable coherence of a vacuum-ultraviolet frequency comb generated through below-threshold harmonics. We find that under reasonable experimental conditions, temporal coherence is maintained. As evidence, we present the first explicit vacuum-ultraviolet frequency-comb structure beyond the third harmonic.
BT - Nature Physics
DA - 2010-11
DO - 10.1038/nphys1398
N2 - Recent demonstrations of high-harmonic generation (HHG) at very high repetition frequencies (approx100 MHz) may allow for the revolutionary transfer of frequency combs to the vacuum-ultraviolet range. This advance necessitates unifying optical frequency-comb technology with strong-field atomic physics. Whereas strong-field studies of HHG have often focused on above-threshold harmonic generation (photon energy above the ionization potential), for vacuum-ultraviolet frequency combs an understanding of below-threshold harmonic orders and their generation process is crucial. Here, we present a new and quantitative study of the harmonics 7–13 generated below and near the ionization threshold in xenon gas with an intense 1,070 nm driving field. We show multiple generation pathways for these harmonics that are manifested as on-axis interference in the harmonic yield. This discovery provides a new understanding of the strong-field, below-threshold dynamics under the influence of an atomic potential and allows us to quantitatively assess the achievable coherence of a vacuum-ultraviolet frequency comb generated through below-threshold harmonics. We find that under reasonable experimental conditions, temporal coherence is maintained. As evidence, we present the first explicit vacuum-ultraviolet frequency-comb structure beyond the third harmonic.
PY - 2009
SP - 815
EP - 820
T2 - Nature Physics
TI - Vacuum-ultraviolet frequency combs from below-threshold harmonics
VL - 5
SN - 1745-2473
ER -