Remotely Induced Atmospheric Lasing

A method for remotely generating a laser pulse in the atmosphere, comprising:

• at time t1, firing a first laser pulse into the atmosphere, the first laser pulse being a pulse from an ultrashort pulse laser (USPL) and being configured to generate a plasma filament at a predetermined location in the atmosphere through ionization of O2 and N2 molecules in the atmosphere, the plasma filament containing a plurality of free electrons generated as a result of the ionization;
• and
• at time t2>t1, firing a second laser pulse into the atmosphere, the second laser pulse being an intense pulse and being configured to form a heater beam that overlaps at least part of the plasma filament so as to thermally excite at least some of the free electrons in the plasma filament;
• wherein the thermally excited electrons collide with other electrons and a plurality of at least one of the O2 and N2 molecules in the filament to collisionally excite a plurality of the at least one of the O2 and N2 molecules in the filament and create a population inversion of excited molecules and cause lasing, the lasing being the result of a relaxation transition of the excited molecules in the filament.

A method for remotely generating a laser pulse in the atmosphere, comprising:

• firing a laser pulse from an ultashort pulse laser (USPL) into the atmosphere, laser pulse being configured to generate a plasma filament at a predetermined location in the atmosphere, the plasma filament containing nitrogen molecules and a plurality of free electrons, the laser pulse being further configured to excite the nitrogen molecules in the plasma filament to produce an upper state populated a plurality of N2+ and N2 molecules;
• wherein the N2+ and N2 molecules undergo a three-body interaction to generate+N4+, which then recombines with an electron to produce an inversion of N2 molecules in the excited C3Πu state;
• and
• wherein the excited N2 molecules undergo a C3Πu→B3Πg(v=0→0) transition of the N2 in the atmosphere to lase at 337 nm.