Femtosecond laser filamentation and supercontinuum generation in strong air turbulence

Abstract

Turbulence is ubiquitous in ambient air and has always posed a great challenge for realizing optical applications in the atmosphere. The refractive index of turbulent air fluctuates randomly has obviously influences on the nonlinear process and characteristics of filamentation, which is a crucial role for many practical applications in free-space atmosphere. In the numerical simulation, we have investigated the filamentation and supercontinuum generation of femtosecond laser pulse with strong atmospheric turbulence in the path of whole the propagation distance. The spatial profile of intensity is analyzed in detail by changing perturbation strength of turbulence. The results show that the laser energy flow distribution presents stronger optical modulation instability with the increase of turbulence intensity in air. Complex spatial multifilament structures are generated by nonlinear propagation in strong turbulent air. The optical intensity along propagation distance significantly decrease as the strength of turbulence increases. The supercontinuum spectrum of filamentation in different strengths turbulence is also investigated. The physical mechanism of supercontinuum intensity change with different strengths of turbulence is discussed. Our results are valuable for realizing the free-space applications based on filamentation and supercontinuum in extreme weather with strong turbulence.