Optimal control of filamentation in air

Abstract

The authors demonstrate optimal control of the propagation of ultrashort, ultraintense (multiterawatt) laser pulses in air over distances up to 36m in a closed-loop scheme. They optimized three spectral ranges within the white-light continuum as well as the ionization efficiency. Optimization results in signal enhancements by typical factors of 2 and 1.4 for the target parameters. The optimization results in shorter pulses by reducing their chirp in the case of white-light continuum generation, while they correct the pulse from its defects and set the filamentation onset near the detector as far as air ionization is concerned

Physics and applications of atmospheric nonlinear optics and filamentation

“…Applications such as high sensitivity multi-pollutant detection with a "whitelight lidar" [95] or molecular coherent control with closed-loop schemes [96,97,98,99] would greatly benefit of a reduced shot-to-shot noise on the supercontinuum intensity. The noise reduction of the spectrally filtered supercontinuum is defined as −10ln V I filament…”

“…The Teramobile team investigated the scalability of the above-described laboratory results to atmospheric problems [99]. Using a SLM and a genetic algorithm, we independently optimized three spectral regions within the white-light continuum, as well as the ionization efficiency, at ~30 m distance.…”

Filament-induced laser machining (FILM)

“…6, although no temporal gating of the blackbody background was used. The characteristic plasma lines for aluminum, copper and stainless steel are clearly identified, allowing on-line analysis of the composition of complex object and even feed back optimization [32] while processing. Traditional temporal gating of the ICCD camera of the spectrometer can obviously be applied to further improve the contrast and identify traces elements within the samples.…”

Filament-based stimulated Raman spectroscopy

“…Femtosecond filamentation results in pulse compression to a duration approaching the single-cycle regime 16,17 , with corresponding spectral broadening from the ultraviolet to the near infrared. The formation distance of the filament and the filament length (as characterized by the fluorescence emission in the plasma channel) from the laser can be controlled optically by manipulating the initial pulse chirp using pulse-shaping techniques 18,19 . Finally, filament formation can be controlled using deformable mirrors 20 .…”