Remote lasing in air by recombination and electron impact excitation of molecular nitrogen

Abstract

We analyze and simulate the physical mechanisms for a remote atmospheric lasing configuration which utilizes a combination of an ultrashort pulse laser to form a plasma filament of seed electrons, and a heater beam to heat the seed electrons. Nitrogen molecules are excited by electron impact and recombination processes to induce lasing in the ultraviolet. Recombination excitation, thermal excitation, gain, and saturation are analyzed and simulated. The lasing gain is sufficiently high to reach saturation within the length of the plasma filament. A remotely generated ultraviolet source may have applications for standoff detection of biological and chemical agents.