Free-Space Nitrogen Laser from a Mid-Infrared Filament

Abstract

We report on laser emission at 337 nm and 357 nm from a filament generated in argonnitrogen mixture by femtosecond mid-infrared pulses. Energies as high as 3.5 J are achieved which corresponds to 0.5% total conversion efficiency from 3.9-µm, 7-mJ 80-fs pulses. Stimulated emission in an argon-nitrogen mixture is also achieved in the case of 1.03-µm 6-mJ 200-fs driving pulses, however only in the presence of multiple filaments and with a far inferior opticalto-optical efficiency. This novel source emitting nanosecond near-UV pulses in the backward, with respect to the driving pulse, direction opens new possibilities remote atmospheric sensing.

Natural population inversion in a gaseous molecular filament

“…In the latter work, amplified spontaneous emission from N 2 and N + 2 was measured. Several recent works also observed gain in N 2 and N + 2 in air [8,9] . However, the mechanism of population inversion in N + 2 has not been completely understood.…”

Harmonic-seeded remote laser emissions in N_2-Ar, N_2-Xe and N_2-Ne mixtures: a comparative study

“…The investigation of lasing from nitrogen molecules can date back to the early 1960s [1,2]. In recent years, technological advances in ultrafast laser source have allowed to access filaments over a distance up to several kilometers [3][4][5], inspiring strong interest in the development of filament-assisted remote laser and its application in standoff spectroscopy [6][7][8][9][10][11][12][13][14][15]. Recent investigations have concentrated on molecular nitrogen laser initiated by amplified spontaneous emission (ASE) with the operation wavelength at ~337 nm or ~357 nm [6][7][8][9][10][11][12] and atomic oxygen laser by ASE at 845 nm [13].…”

“…In recent years, technological advances in ultrafast laser source have allowed to access filaments over a distance up to several kilometers [3][4][5], inspiring strong interest in the development of filament-assisted remote laser and its application in standoff spectroscopy [6][7][8][9][10][11][12][13][14][15]. Recent investigations have concentrated on molecular nitrogen laser initiated by amplified spontaneous emission (ASE) with the operation wavelength at ~337 nm or ~357 nm [6][7][8][9][10][11][12] and atomic oxygen laser by ASE at 845 nm [13]. The former is based on the electron recombination of ionized molecular nitrogen [6][7][8][9] or thermal electron collisional excitation [10][11][12], and the latter is realized by simultaneous dissociation of molecular oxygen and excitation of atomic oxygen using a picosecond 226 nm-laser beam [13].…”

“…Recent investigations have concentrated on molecular nitrogen laser initiated by amplified spontaneous emission (ASE) with the operation wavelength at ~337 nm or ~357 nm [6][7][8][9][10][11][12] and atomic oxygen laser by ASE at 845 nm [13]. The former is based on the electron recombination of ionized molecular nitrogen [6][7][8][9] or thermal electron collisional excitation [10][11][12], and the latter is realized by simultaneous dissociation of molecular oxygen and excitation of atomic oxygen using a picosecond 226 nm-laser beam [13].…”

Ultrafast-laser-induced backward stimulated Raman scattering for tracing atmospheric gases

“…However, an observer who sends out a laser pulse to interrogate an optically transparent atmosphere has to find an alternative way of initiating a backward-propagating laser beam and to solve the problem of phase matching. The recent experimental demonstration of a remotely pumped atmospheric backward laser using O 2 (λ=845 nm) [1] or N 2 (λ=337 and 357 nm) [2] has sparked proposals for coherent standoff Raman spectroscopies [3].…”