Thermal blooming in gases

Glass, Alexander J.

doi:10.1007/bf01834679

Cited by 11 publications

(1 citation statement)

References 11 publications

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“…In some cases the interaction results in instabilities [1,2], while in others the laser beam self-focuses [3], and there are still other cases where it defocuses [4,5]. The beam is modified according to the physical properties of the medium in addition to the initial parameters of the beam itself.…”

Section: Introductionmentioning

confidence: 99%

Determination of absorption coefficient based on laser beam thermal blooming in gas-filled tube

et al. 2014

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Thermal blooming of a laser beam propagating in a gas-filled tube is investigated both analytically and experimentally. A self-consistent formulation taking into account heating of the gas and the resultant laser beam spreading (including diffraction) is presented. The heat equation is used to determine the temperature variation while the paraxial wave equation is solved in the eikonal approximation to determine the temporal and spatial variation of the Gaussian laser spot radius, Gouy phase (longitudinal phase delay), and wavefront curvature. The analysis is benchmarked against a thermal blooming experiment in the literature using a CO₂ laser beam propagating in a tube filled with air and propane. New experimental results are presented in which a CW fiber laser (1 μm) propagates in a tube filled with nitrogen and water vapor. By matching laboratory and theoretical results, the absorption coefficient of water vapor is found to agree with calculations using MODTRAN (the MODerate-resolution atmospheric TRANsmission molecular absorption database) and HITRAN (the HIgh-resolution atmospheric TRANsmission molecular absorption database).

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