Coupled air lasing gain and Mie scattering loss: an aerosol effect in filament-induced plasma spectroscopy.

Femtosecond laser filament-induced plasma spectroscopy (FIPS) demonstrates great potential in remote sensing for identifying atmospheric pollutant molecules. Due to the widespread aerosols in the atmosphere, remote detection based on FIPS would be affected by both the excitation and the propagation of fingerprint fluorescence, which still remain elusive. Here the physical model of filament-induced aerosol fluorescence is established to reveal the combined effect of Mie scattering and amplification spontaneous emission, which is subsequently proven by experimental results, the dependence of the backward fluorescence on the interaction length between filaments and aerosols. These findings provide an insight into the complicated aerosol effect in the overall physical process of FIPS including propagation, excitation, and emission, paving the way to its practical application in atmospheric remote sensing.