Light self-focusing in the atmosphere: thin window model.

Irina A Vaseva,Mikhail P Fedoruk,Alexander M Rubenchik,Sergei K Turitsyn

doi:10.1038/srep30697

Abstract

Ultra-high power (exceeding the self-focusing threshold by more than three orders of magnitude) light beams from ground-based laser systems may find applications in space-debris cleaning. The propagation of such powerful laser beams through the atmosphere reveals many novel interesting features compared to traditional light self-focusing. It is demonstrated here that for the relevant laser parameters, when the thickness of the atmosphere is much shorter than the focusing length (that is, of the orbit scale), the beam transit through the atmosphere in lowest order produces phase distortion only. This means that by using adaptive optics it may be possible to eliminate the impact of self-focusing in the atmosphere on the laser beam. The area of applicability of the proposed “thin window” model is broader than the specific physical problem considered here. For instance, it might find applications in femtosecond laser material processing.

Highlights

Ultra-high power light beams from ground-based laser systems may find applications in space-debris cleaning
We show here that the thin window” (TW) model prediction is in excellent agreement with solutions of the exact nonlinear Schrödinger equation (NLSE)
We present simple analytical expressions for these important practical parameters based on TW model and verify their applicability through numerical modeling using NLSE

Summary

Introduction

Ultra-high power (exceeding the self-focusing threshold by more than three orders of magnitude) light beams from ground-based laser systems may find applications in space-debris cleaning. The self-focusing length in this situation is much longer than the atmospheric thickness, and nonlinear effects produce only phase aberrations, which during the following long (about 1000 km) free propagation to the debris can greatly modify the beam (see Fig. 1). One can see that as a result of the nonlinear focusing in the atmosphere, the intensity peak moves back to the ground, and at high power when filamentation becomes important, the transverse beam shape is far from Gaussian.

Results

Conclusion