Propagation Of Intense Ultrashort Laser Pulses In The Atmosphere

A stable plasma channel is formed when ultra-short high power laser propagates in the atmosphere, which meanwhile leads to a variety of physical phenomena, such as supercontinuum spectrum generation, third-order harmonic generation, conical emission. These phenomena have broad application prospects in laser triggered lightning, laser-induced lightning, laser-induced nuclear reactions, long-distance energy transmission of high power laser, etc. Therefore, the research of propagation of ultra-high power and ultrashort pulse laser in the atmosphere has become a new hot spot in laser physics.Based on an extended spatial dynamic compensation model, this paper mainly discusses the evolution and control of laser-plasma channel which formed by the propagation of ultrashort intense laser pulse in the atmosphere. It is now widely believed that the formation of plasma channel in air is mainly due to the combined action of diffraction, dispersion, Kerr effect and multi-photon absorption. In this paper, besides the basis important mechanism above, Raman scattering, plasma wake fields, relativistic focusing and other effects are also taken into consideration. Using a reasonable approximation, we amend the nonlinear Schr(o|¨)dinger equation that governs the propagation of ultrashort laser pulse in the atmosphere. Split-step Fourier and differential method have been applied to gain both two-dimensional and three-dimensional numerical simulation results. Flux of light intensity and electron density distribution in space as well as pulse evolution in time and space are discussed. Through numerical simulation, it reveals that different initial parameters of pulse such as wavelength, input pulse energy, pulse width and waist, may have influence on the filamentation. A prospect of other complicated methods that may vary the filament distribution was also made, such as adopting temporally chirped initial pulse, inducing subsequent pulse to form twin laser pulses. These work might add a new path to the exploration of the position and shape control of ultra-short laser pulses filamentation in the atmosphere.