Mid-infrared laser filaments in the atmosphere

TL;DR

This paper reports the first demonstration of mid-infrared laser filamentation in the atmosphere, enabling high-energy, high-power transmission with broad supercontinuum generation from visible to mid-infrared wavelengths.

Contribution

It introduces the first successful atmospheric filamentation of ultrashort mid-infrared pulses at 3.9 μm, expanding the wavelength range for filamentation experiments.

Findings

Achieved over 20 mJ pulse energy and 200 GW peak power in a single filament.

Generated a broad supercontinuum spectrum from visible to mid-infrared.

Demonstrated unique harmonic generation phenomena in mid-infrared filaments.

Abstract

Filamentation of ultrashort laser pulses in the atmosphere offers unique opportunities for long-range transmission of high-power laser radiation and standoff detection. With the critical power of self-focusing scaling as the laser wavelength squared, the quest for longer-wavelength drivers, which would radically increase the peak power and, hence, the laser energy in a single filament, has been ongoing over two decades, during which time the available laser sources limited filamentation experiments in the atmosphere to the near-infrared and visible ranges. Here, we demonstrate filamentation of ultrashort mid-infrared pulses in the atmosphere for the first time. We show that, with the spectrum of a femtosecond laser driver centered at 3.9 um, right at the edge of the atmospheric transmission window, radiation energies above 20 mJ and peak powers in excess of 200 GW can be transmitted through the atmosphere in a single filament. Our studies reveal unique properties of mid-infrared filaments, where the generation of powerful mid-infrared supercontinuum is accompanied by unusual scenarios of optical harmonic generation, giving rise to remarkably broad radiation spectra, stretching from the visible to the mid-infrared.