Regions of spreading of partially coherent beams propagating through non-Kolmogorov turbulence

In this paper, the regions of spreading of partially coherent beams propagating through non-Kolmogorov turbulence are examined by using the turbulence distances zT and zTT. The spreading is less affected by atmospheric turbulence (AT) when zzTT. The dependence of zT and zTT on the turbulence parameters and the beam parameters is studied in detail. It is found that both zT and zTT reach their minimums when the fractal constant of the atmospheric power spectrum is equal to 3.11. However, the dependence of zTT on turbulence parameters and beam parameters is much larger than that of zT. There exists a minimum of zT versus the waist width, but zTT decreases monotonically as the waist width increases. On the other hand, the relation between the turbulence distance zT and the Rayleigh range zR is investigated. It is shown that zT=zR may appear when a suitable waist width or a suitable coherent parameter is chosen. For the small free-space diffraction (FD) case zTzR. Some physical explanations for the results obtained in this paper are also given.