Backward stimulated radiation from filaments in Nitrogen gas and air pumped by circularly polarized 800 nm femtosecond laser pulses

Abstract

We report on strong backward stimulated emission at 337 nm in Nitrogen gas pumped by circularly polarized femtosecond laser pulses at 800 nm. A distinct dependence of the backward UV spectrum on pump laser polarization and intensity is observed, pointing to the occurrence of backward amplified spontaneous emission inside filaments. We attribute the population inversion to inelastic collision between the free electrons produced by the pump laser and neutral N2 molecules. The addition of Oxygen molecules is detrimental for the gain, reducing it to near threshold at atmospheric concentration.

References in corpus (4)

• Self-seeded lasing in ionized air pumped by 800 nm femtosecond laser pulses
• Lasing of ambient air with microjoule pulse energy pumped by a multi terawatt IR femtosecond laser
• Self-induced white-light seeding laser in a femtosecond laser filament
• Impulsive rotational Raman scattering of N2 by a remote "air laser" in femtosecond laser filament

Cited by in corpus (12)

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• Gain dynamics of a free-space nitrogen laser pumped by circularly polarized femtosecond laser pulses
• Coherent control of superradiance from nitrogen ions pumped with femtosecond pulses
• Exit momentum and instantaneous ionization rate of nonadiabatic tunneling ionization in elliptically polarized laser fields
• Femtosecond two-photon-excited backward lasing of atomic hydrogen in flame
• Polychromatic, continuous-wave mirrorless lasing from monochromatic pumping of cesium vapor
• Laser Driven Fluorescence Emission in a Nitrogen Gas Jet at 100 MHz Repetition Rate
• Ramsey interferometry through coherent $X^2{\Sigma }_g^{+}-A^2{\Pi }_u-B^2{\Sigma }_u^{+}$ coupling and population transfer in N${}_2^{+}$ air laser
• Optical vortex coronagraph imaging of a laser-induced plasma filament
• Externally seeded backward lasing radiation from femtosecond laser filament in nitrogen gas
• Backward air lasing actions induced by femtosecond laser filamentation: influence of population inversion lifetime