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Photonics

ALTESSE

Terahertz spectroscopy of explosives from air plasmas

Identifying energetic materials is a major challenge for dual civilian and military research in order to keep populations safe. One of the primary goals in this context is to measure the spectral signatures of explosives at remote distances.

Terahertz (THz) waves offer a high level of selectiveness in the rotational and vibrational transitions of complex molecules. The ALTESSE project has proved that many macromolecules, either explosives, amino acids or sugars, can be identifi ed in this spectral domain using an air plasma formed by two-color femtosecond laser pulses.

ALTESSE has led to major scientific breakthroughs, including spectroscopy of explosives 15 metres away from the laser source, the acquisition of multiple absorption lines from the terahertz to the mid-infrared range, and an important increase in the radiation emitted at high laser wavelengths.

The project

ANR programme: ASTRID (and then Maturation from 2019)
Fully funded by the Direction générale de l’Armement

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Edition, project duration: 2015, 36 months

Subvention ANR: € 299,142 

Coordinator:

  • Luc Bergé
    Commissariat à l’énergie atomique et aux énergies alternatives
    luc.berge@cea.fr

Project regions: Île-de-France • Nouvelle-Aquitaine • Grand Est

Main publication or contribution:

  • L. Bergé, K. Kaltenecker, S. Engelbrecht, A. Nguyen, S. Skupin, L. Merlat, B. Fischer, B. Zhou, I. Thiele and P. U. Jepsen, “Terahertz spectroscopy from air plasmas created by two-color femtosecond laser pulses: The ALTESSE project“, EuroPhys. Lett. 126, 24001 (2019).
  • 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, and L.  Bergé, “Wavelength scaling of terahertz pulse energies delivered by two-color air plasmas”, Opt. Lett. 44, 1488 (2019).

Partners: 

  • CEA – Direction Ile-de-France.
  • CEntre des Lasers Intenses et Applications (CELIA).
  • Institut franco-allemand de recherches de Saint-Louis (ISL).
  • Danish Technical University (DTU) – Lyngby – Danemark
ALTESSE
Terahertz absorption spectrum measured from air-plasma THz radiation (black curves) and simulated phonon modes (ab-initio code, red bars) for a TATB sample. On the right, characteristic molecular structure of TATB with dipole excitations. © EuroPhysicsLetters
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The next phase of the project will exploit the fi lamentation regime using a power fi bre laser source and ab-initio simulations will allow a more precise allocation of molecular absorption lines. ALTESSE should pave the way for the creation of a demonstrator for the remote identifi cation of explosives and the manipulation of molecules using terahertz radiation.

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