Coherent Secondary Radiation from Femtosecond Laser Filaments

Sergey Mitryukovskiy 1
1 ILM - Interaction Laser-Matière
LOA - Laboratoire d'optique appliquée
Abstract : Laser filamentation is a nonlinear optical phenomenon which appears spontaneously during the propagation of an intense ultrashort laser pulse in a transparent medium, when the pulse peak power exceeds a critical value (several Gigawatts in air). At such an intensity level the beam tends to collapse due to the optical Kerr self-focusing effect until the intensity is high enough to ionize the medium, giving rise to a defocusing plasma. Thereafter, a dynamic competition between these two effects takes place, leaving a thin and weakly ionized plasma channel in the wake of the pulse. Following its discovery in 1995, femtosecond laser filamentation in air has attracted considerable interest because of the rich physics involved in the process and the wide range of potential applications (remote sensing, light frequency conversion, laser-based weather control, Terahertz generation, etc.).This thesis is devoted to the study of the coherent secondary emission from femtosecond laser filaments in gases. First, the ultraviolet luminescence of plasma filaments, corresponding to transitions of excited neutral and ionic molecular Nitrogen, is studied. I demonstrate that this luminescence depends strongly on the polarization state of the incident laser pulses. I further report and interpret for the first time a strong optical gain in the backward direction from plasma filaments created by circularly polarized 800 nm femtosecond laser pulses at normal pressure. This effect is a significant step towards the realization of a “laser in the sky”. In the last part of the thesis, I discuss the Terahertz generation from multiple femtosecond laser filaments in air. The coherent synthesis of the Terahertz radiation from an array of filaments is demonstrated, showing the capability for energy scaling up and directionality control of the Terahertz emission.
Complete list of metadatas

Cited literature [250 references]  Display  Hide  Download

https://pastel.archives-ouvertes.fr/tel-01091553
Contributor : Sergey Mitryukovskiy <>
Submitted on : Friday, December 5, 2014 - 4:05:14 PM
Last modification on : Wednesday, July 3, 2019 - 10:48:04 AM
Long-term archiving on : Monday, March 9, 2015 - 6:04:24 AM

Identifiers

  • HAL Id : tel-01091553, version 1

Collections

Citation

Sergey Mitryukovskiy. Coherent Secondary Radiation from Femtosecond Laser Filaments. Physics [physics]. École Polytechnique, 2014. English. ⟨tel-01091553⟩

Share

Metrics

Record views

649

Files downloads

898