Laser beam self-focusing in turbulent dissipative media

Abstract

A high-power laser beam propagating through a dielectric in the presence of fluctuations is subject to diffraction, dissipation, and optical Kerr nonlinearity. A method of moments was applied to a stochastic, nonlinear enveloped wave equation to analyze the evolution of the long-term spot radius. For propagation in atmospheric turbulence described by a Kolmogorov-von Kármán spectral density, the analysis was benchmarked against field experiments in the low-power limit and compared with simulation results in the high-power regime. Dissipation reduced the effect of self-focusing and led to chromatic aberration.

Theoretical analysis on small-scale self-focusing of multi-wavelength beams in an isotropic medium

“…The self-focusing of high power lasers is a classical course for nonlinear optics. There have been intensive investigations, both theoretical and experimental, with regard to the self-focusing phenomena in laser propagation from 1960s onwards [1][2][3][4][5][6][7][8][9][10]. Maxwell equations are the basic theories for nonlinear optics, and they have been greatly developed for different applications over the past 40 years.…”

“…According to differences in the phenomenon, some unique analysis methods have been constructed. The aperture of self-focusing contains whole beam self-focusing [20,21] and small-scale self-focusing [1,3]; the response time of material polarization contains the two options of steady state for nanosecond or even longer pulses [1,2] and transient state for picosecond or even shorter pulses [1,22,23]; the degree of beam diffraction contains plane wave beam self-focusing [1,2] and tapered beam self-focusing [24,[27][28][29]; interaction includes the variants of single-wavelength beam self-focusing [1][2][3][4][5][6][7][8][9][10][11][12][13] and multi-wavelength beam self-focusing [25,26].…”

Beating Optical-Turbulence Limits Using High-Peak-Power Lasers

“…For linear propagation over a long distance, natural diffraction increases the beam size to a point where this condition eventually can no longer be met. However, this is not the case for a nonlinear self-channeling beam, which can maintain its size over long distances by using nonlinear self-focusing to balance out diffraction [12,13]. This condition is met when the peak power is equal to the critical power in air, ∼5GW [14].…”

Critical power for self-focusing of optical beam in absorbing media

“…In addition, self-focusing is also crucial for many applications in laser physics such as Kerr-lens mode locking [11], chirped pulse amplification, self-compression of ultra-short laser pulses [12], parametric generation [13], and many areas of laser-matter interaction. As a consequence, self-focusing is of central importance for most nonlinear optical effects and corresponding applications, and thus persistent research has been undertaken, both theoretically and experimentally [14][15][16][17].…”