Simulating a 980 nm laser beam propagation through humid air

J. Alameri; A. Bouchalkha; J. Coronel; J. Galvis; G. Matras; S. Cordette; C. Kasmi; A. Dubey

doi:10.1117/12.2594402

1 August 2021 Simulating a 980 nm laser beam propagation through humid air

J. Alameri, A. Bouchalkha, J. Coronel, J. Galvis, G. Matras, S. Cordette, C. Kasmi, A. Dubey

Proceedings Volume 11834, Laser Communication and Propagation through the Atmosphere and Oceans X; 118340N (2021) https://doi.org/10.1117/12.2594402
Event: SPIE Optical Engineering + Applications, 2021, San Diego, California, United States

Abstract

Laser propagation through a medium is often accurately explained by geometrical optics where light is described as rays. When considering wave diffraction, a more generalized description of physical optics is used. Faced with the complexity of interactions of a laser beam with the atmosphere, and the additional challenges of deploying a physical high power laser system for advanced evaluation in harsh environment, the use of simulation software is preferred to study and predict the behavior of the beam propagation in atmosphere. In this paper, we show that the intensity and diffraction of a laser beam in the atmosphere can be properly described by geometrical optics when coupled with an appropriate model of the variations of the index of refraction, heat convection velocity, and atmospheric relative humidity. The study uses a Near Infrared (NIR) laser source at 980 nm of 1 kW average power. The laser beam propagation was implemented using a finite element model developed with a COMSOL multi-physics ray tracing model in both transient and steady-state regimes. The beam divergence from the center of the propagation path was clearly observed when the crosswind velocity inside the domain was greater than 10 m/s while having 300K temperature at 1 atm pressure as initial conditions. The direction and amount of divergence are observed to be directly linked to the velocity of the cross-wind, as well as the refractive index variations due to the amount of humidity in the air, and the heat generated by the laser beam in the atmosphere. According to our results, the higher the humidity of the air is, the more energy is deposited in the atmosphere resulting in the reduction of the accumulated power on the target.

Conference Presentation

Citation Download Citation

J. Alameri, A. Bouchalkha, J. Coronel, J. Galvis, G. Matras, S. Cordette, C. Kasmi, and A. Dubey "Simulating a 980 nm laser beam propagation through humid air", Proc. SPIE 11834, Laser Communication and Propagation through the Atmosphere and Oceans X, 118340N (1 August 2021); https://doi.org/10.1117/12.2594402

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