Presentation
13 March 2019 Nonlinear transient properties of laser induced waveguides (Conference Presentation)
Jean-Claude M. Diels, Ladan Arissian, Brian Kamer, Ali Rastegari
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Abstract
The challenge of guiding or deflecting a laser beam in a disturbed medium involves careful consideration of various nonlinear interactions of light with air and their transient response. A light filament provides a high intensity region in space that maintain its shape for propagation lengths longer than the Rayleigh range. The possibility to use this light channel for coupling optical, teraherz and radio frequency had been spurring researches in this field. We present the contribution of transient nonlinear response of the medium on light propagation. The nonlinear interaction of ultrashort pulses with air leaves a spatial distribution of ionized medium that evolves into an equilibrium plasma. The light pulse has left the medium it ionized before the plasma has reached equilibrium. Therefore, the reaction of the medium onto the filament involves a transient evolution of the ensemble of ions and electrons that follow deterministic trajectories under the influence of the light field. Other nonlinear interactions such as molecular alignment also have a time dependent response. The relative influence of the plasma and molecular motion is modified by focusing conditions. The standard focusing of light into air combines the nonlinear Kerr focusing with the desired linear focusing of the optics. A focusing through a sharp pressure gradient made by an aerodynamic window enhances the pointing stability of the laser beam. The effect of transient response of the medium driven by nonlinear interaction of ultrashort pulse on the guided beam will be discussed.
Conference Presentation
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Jean-Claude M. Diels, Ladan Arissian, Brian Kamer, and Ali Rastegari "Nonlinear transient properties of laser induced waveguides (Conference Presentation)", Proc. SPIE 10904, Laser Resonators, Microresonators, and Beam Control XXI, 109040B (13 March 2019); https://doi.org/10.1117/12.2514633
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KEYWORDS
Waveguides

Plasma

Geometrical optics

Radio propagation

Transient nonlinear optics

Ultrafast phenomena

Channel projecting optics

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