Beam spreading of vortex beams propagating in turbulent atmosphere

Abstract

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.

Numerical simulation of optical vortex propagation and reflection by the methods of scalar diffraction theory

“…Description of scalar and vector diffraction of coherent light on a spiral phase plate in the thin optical element approximation is given in [5]. Recently, Lukin et al [6] have presented the results of numerical modelling of propagation of scalar Laguerre - Gauss coherent vortices through turbulent atmosphere. However, the process of reflection of spiral wavefronts from rough surfaces, as far as we know, has not been analysed.…”

850-nm hybrid fiber/free-space optical communications using orbital angular momentum modes

“…7. Thus, for instance, in the case of moderate turbulence (σ 2 I = 0.406), behaviors associated to each mode are almost the same whereas, for the case of very weak turbulence ((σ 2 I = 0.01), a remarkable improvement in BER is reported (around 4 dBm between OAM M3 and OAM M0 for an error probability of 2 · 10 −2 ), as a direct consequence of a faster divergence, a larger delay and a beam spreading [34] suffered by higher-order OAM modes. Consequently, although all OAM modes are subjected to increased attenuation with increased turbulence strength, however higher-order modes are more strongly affected, being also consistent with Anguita's work [26].…”

Evolution Properties of a Partially Coherent Flat-topped Vortex Hollow Beam Propagating in Uniaxial Crystals Orthogonal to the Optical Axis

“…Among the optical vortex beams, the properties of the elliptical Gaussian vortex beam [12], partially coherent four-petal Gaussian vortex beam [18], four-petal Gaussian vortex beam [19], vortex beam carried by an Airy beam [20], vortex beams [21], and partially coherent hollow vortex Gaussian beam [22], have been studied. However, to our knowledge, there have been no reports about partially coherent flat-topped vortex hollow beams propagating in uniaxial crystals orthogonal to the optical axis.…”