Мақола

Enhanced Harmonic Generation from Expanding Clusters

Bonggu ShimFOCUS Center, Department of Physics, University of Texas at Austin, Austin, Texas 78712-1081, USAGraeme C. HaysFOCUS Center, Department of Physics, University of Texas at Austin, Austin, Texas 78712-1081, USARafal ZgadzajFOCUS Center, Department of Physics, University of Texas at Austin, Austin, Texas 78712-1081, USAT. DitmireFOCUS Center, Department of Physics, University of Texas at Austin, Austin, Texas 78712-1081, USAM. C. DownerFOCUS Center, Department of Physics, University of Texas at Austin, Austin, Texas 78712-1081, USA

2007en

ABI

Аннотация

We report controlled enhancement of optical third harmonic generation (THG) from hydrodynamically expanding clusters of approximately 6x10(5) noble-gas atoms several hundred femtoseconds following ionization and heating by ultrashort pump pulses. This resonant enhancement is more pronounced for orthogonal than for parallel pump-probe polarizations, a consequence of faster cluster expansion along the pump polarization. Simulations show that the nonlinear susceptibility chi(3) of the individual clusters and the coherence length of the clustered plasma medium are optimized nearly simultaneously as the clusters expand, and both contribute to the observed THG enhancement. This dual enhancement mechanism may be scalable to relativistic probe intensity and to generation of high-order harmonics in the soft-x-ray regime.

Идентификаторлар

DOI: 10.1103/physrevlett.98.123902

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