Beam spreading of vortex beams propagating in turbulent atmosphere Vladimir P. Lukin,* Peter A. Konyaev, and Victor A. Sennikov V.E. Zuev Institute of Atmospheric Optics SB RAS, 1 Academician Zuev Square, Tomsk 634021, Russia *Corresponding author: lukin@iao.ru Received 13 December 2011; accepted 5 January 2012; posted 27 January 2012 (Doc. ID 159900); published 27 March 2012 We present some results obtained by numerical modeling of the propagation of vortex beams LG 0l through a randomly inhomogeneous medium. The vortex beams are the lower order Laguerre–Gaussian modes. Such beams, if propagated under conditions of weak turbulence, also experience distortions, like a Gaussian beam. However, the statistically averaged vortex beams (LG 0l ) conserve the central intensity dip with a nonzero intensity on the beam axis. The beam broadening of vortex beams is analyzed. The average vortex beams are found to be broadened less than the Gaussian beam while propagated through a randomly inhomogeneous medium. The higher the topological charge l is, the smaller the beam broadening is. © 2012 Optical Society of America OCIS codes: 010.1330, 010.1300, 030.7060. 1. Introduction In recent years, interest has increased in the studies of non-Gaussian laser beam propagation through turbulent atmosphere. In particular, it is caused by the search for new types of laser beams for use in optical communication. The studies in [ 1– 3] are ana- lytical investigations into the properties of the higher order annular Gaussian beams (HOAG beams ac- cording to the terminology in these papers) propa- gated through the turbulent atmosphere. It was noted that at their propagation through the turbu- lent atmosphere, the time-averaged intensity of such beams undergoes some stages of evolution. The aver- aged beam energy tends to concentrate near the axis at intermediate distances of propagation. Thus, the main averaged beam is formed. Finally, when propa- gated at a significant distance, the initial HOAG beam becomes a purely Gaussian averaged beam [ 3– 5]. In [ 4], the propagation properties of tubular light beams of round, elliptical, and square-shaped cross sections were investigated analytically. Recently, the light beams transferring the optical vortices [ 6– 8] have attracted a great interest. The low- er order Laguerre–Gaussian modes LG 0l of a laser re- sonator can serve as an example for such beams. Their intensity distribution forms a ring and their phase covers a spiral surface because of the optical vortex on the beam axis. The effect of a central dip and vortex on the Gaussian beam properties was investigated in [ 9], and it was shown that the vortex worsens the beam quality as compared with the quality of an or- dinary Gaussian beam. Nevertheless, the unique capability of the beams that transfer the optical vor- tices to transfer their orbital angular momentum (OAM) had caused a large development in singular optics [ 10– 12] and its various practical applications, including the so-called optical tweezers [ 6– 8]. The beams can be obtained in several ways: by means of computer-synthesized holograms and diffraction op- tics [ 10], at conversion of Hermite–Gaussian modes [ 11] and so on. Various ways of their formation are being developed and improved. In recent years, use of the OAM [ 12] transferred by the light beam with optical vortex has been actively investigated. It appears essential for information coding in lines of optical communication. It was 1559-128X/12/100C84-04$15.00/0 © 2012 Optical Society of America C84 APPLIED OPTICS / Vol. 51, No. 10 / 1 April 2012