Wavelength scaling of terahertz pulse energies delivered by two-color air plasmas

A. Nguyen, K. J. Kaltenecker, J. C. Delagnes, B. Zhou, E. Cormier, N. Fedorov, R. Bouillaud, D. Descamps, I. Thiele, S. Skupin, P. U. Jepsen, L. Bergé*

*Corresponding author for this work

Research output: Contribution to journalJournal articleResearchpeer-review

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We address the long-standing problem of anomalous growth observed in the terahertz (THz) energy yield from air plasmas created by two-color laser pulses, as the fundamental wavelength λ 0 is increased. Using two distinct optical parametric amplifiers (OPAs), we report THz energies scaling like λ α 0 with large exponents 5.6 ≤ α ≤ 14.3, which departs from the growth in λ 2 0 expected from photocurrent theory. By means of comprehensive 3D simulations, we demonstrate that the changes in the laser beam size, pulse duration, and phase-matching conditions in the second-harmonic generation process when tuning the OPA’s carrier wavelength can lead to these high scaling powers. The value of the phase angle between the two colors reached at the exit of the doubling crystal turns out to be crucial and even explains non-monotonic behaviors in the measurements.

Original languageEnglish
JournalOptics Letters
Issue number6
Pages (from-to)1488-1491
Number of pages4
Publication statusPublished - 1 Jan 2019


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