Details

Autor(en) / Beteiligte

• Shim, B
• Hays, G
• Zgadzaj, R
• Ditmire, T
• Downer, M C

Titel

Enhanced harmonic generation from expanding clusters

Ist Teil von

• Physical review letters, 2007-03, Vol.98 (12), p.123902-123902, Article 123902

Ort / Verlag

United States

Erscheinungsjahr

2007

Quelle

APS Journals (American Physical Society)

Beschreibungen/Notizen

• 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.