Space-based Femtosecond Laser Filamentation

This study aimed at developing the numerical framework to investigate whether the remote generation of laser filaments from orbital altitude was theoretically feasible and in this case to gain insights on the required initial laser parameters to remotely generate a filament. In this work the state-of-the-art theory on self-focusing, filamentation and collapse has been extended to long-distance propagation of ultrashort laser pulses in a stratified atmosphere. The model consists of a unidirectional propagation equation with a medium's response model and includes diffraction laws, optical Kerr effect, plasma defocusing, multispecies ionisation and multiphoton absorption. Propagation in the stratified atmosphere was taken into account via an air density profile depending on the molecule type and altitude profile. Supercontinuum generation was studied by adding the temporal dimension to the simulations, accounting for group velocity dispersion in air and the resulting spectral broadening.