Harmonic-seeded remote laser emissions in N2-Ar, N2-Xe and N2-Ne   mixtures: a comparative study
  We report on the investigation on harmonic-seeded remote laser emissions at 391 nm wavelength from strong-field ionized nitrogen molecules in three different gas mixtures, i.e., N2-Ar, N2-Xe and N2-Ne. We observed a decrease in the remote laser intensity in the N2-Xe mixture because of the decreased clamped intensity in the filament; whereas in the N2-Ne mixture, the remote laser intensity slightly increases because of the increased clamped intensity within the filament. Remarkably, although the clamped intensity in the filament remains nearly unchanged in the N2-Ar mixture because of the similar ionization potentials of N2 and Ar, a significant enhancement of the lasing emission is realized in the N2-Ar mixture. The enhancement is attributed to the stronger third harmonic seed, and longer gain medium due to the extended filament. 
Jielei Ni, Wei Chu, Haisu Zhang, Chenrui Jing, Jinping Yao, Huailiang   Xu, Bin Zeng, Guihua Li, Chaojin Zhang, See Leang Ch...
physics.optics physics.atom-ph