Journal article
Wavelength scaling of terahertz pulse energies delivered by two-color air plasmas
French Alternative Energies and Atomic Energy Commission1
Department of Photonics Engineering, Technical University of Denmark2
Ultrafast Infrared and Terahertz Science, Department of Photonics Engineering, Technical University of Denmark3
Center for Nanostructured Graphene, Centers, Technical University of Denmark4
Université de Bordeaux5
Chalmers University of Technology6
Universite Claude Bernard Lyon 17
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.
Language: | English |
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Year: | 2019 |
Pages: | 1488-1491 |
ISSN: | 15394794 and 01469592 |
Types: | Journal article |
DOI: | 10.1364/OL.44.001488 |
ORCIDs: | 0000-0003-0400-8213 , Zhou, B. , 0000-0003-0474-0551 , 0000-0002-3189-9608 , 0000-0002-9215-1150 , 0000-0002-5531-7692 and Jepsen, P. U. |