Megafilament in air formed by self-guided terawatt long-wavelength infrared laser

Sergei Tochitsky, Eric Welch, Mikhail Polyanskiy, Igor Pogorelsky, Paris Panagiotopoulos, Miroslav Kolesik, Ewan M. Wright, Stephan W. Koch, Jerome V. Moloney, Jeremy Pigeon, Chan Joshi

Research output: Contribution to journalArticlepeer-review

64 Scopus citations


The diffraction-compensated propagation of high-power laser beams in air could open up new opportunities for atmospheric applications such as remote stand-off detection, long-range projection of high-energy laser pulses and free-space communications. Here, we experimentally demonstrate that a self-guided terawatt picosecond CO 2 laser beam forms in air a single centimetre-scale-diameter megafilament that, in comparison with a short-wavelength laser filament, has four orders of magnitude larger cross-section and guides many joules of pulse energy over multiple Rayleigh distances at a clamped intensity of ~10 12 W cm –2 . We discover that this megafilament arises from the balance between self-focusing, diffraction and defocusing caused by free carriers generated via many-body Coulomb-induced ionization that effectively decrease the molecular polarizability during the long-wavelength laser pulse. Modelling reveals that this guiding scheme may enable transport of high-power picosecond infrared pulses over many kilometres in the 8–14 μm atmospheric transmission window.

Original languageEnglish (US)
Pages (from-to)41-46
Number of pages6
JournalNature Photonics
Issue number1
StatePublished - Jan 1 2019

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Atomic and Molecular Physics, and Optics


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