The propagation effects of spatially pseudo-partially coherent Gaussian Schell-model beams in atmosphere are investigated numerically. The characteristics of beam spreading, beam wandering and intensity scintillation are analyzed respectively. It is found that the degradation of degree of source coherence may cause reductions of relative beam spreading and scintillation index, which indicates that partially coherent beams are more resistant to atmospheric turbulence than fully coherent beams. And beam wandering is not much sensitive to the change of source coherence. However, a partially coherent beam have a larger spreading than the fully coherent beam both in free space and in atmospheric turbulence. The influences of changing frequency of random phase screen which models the source coherence on the final intensity pattern are also discussed.

Propagation properties of spatially pseudo-partially coherent Gaussian Schell-model beams through the atmospheric turbulence over a long-distance uplink path are studied by numerical simulation. A linear coordination transformation is introduced to overcome the window effect and the loss-of-resolution problem. The beam spreading, beam wandering, and intensity scintillation as functions of turbulence strength, source correlation length, and change frequency of random phase that models the partial coherence of the source are analyzed. It is found that the beam spreading and the intensity scintillation of the partially coherent beam are less affected by the turbulence than those of the coherent one, but it suffers from a more severe diffractive effect, and the change frequency of random phase has no evident influence on it. The beam wandering is insensitive to the variation of source correlation length, and decreases firstly then goes to a fixed value as the change frequency increases.

The distribution of optical turbulence ( C n 2 profiles) is the fundamental parameter closely related to the design and application of optoelectronic systems. Since systematic direct measurements of optical turbulence for many climates and seasons are not available, it is useful to estimate C n 2 effectively from the routine meteorological parameters. The C n 2 profiles are estimated by routine meteorological parameters based on the Tatarskii model, and the estimated results are compared with the corresponding radiosonde measurements from the field campaigns at Rongcheng ( 122.37 ∘ E , 37.15 ∘ N ), Taizhou ( 121.42 ∘ E , 28.62 ∘ N ), and Dachaidan ( 95.35 ∘ E , 37.74 ∘ N ) in China. The agreement between the estimation model and the measurement is very close, except for a portion of the atmosphere where it showed considerable difference. Additionally, statistical operators are used to quantify the performance of the estimated model, and the statistical results also show that the estimated and measured C n 2 profiles are consistent well. Furthermore, the integrated parameters (such as the Fried parameter, r 0 ) from radiosonde measurement are 7.92 cm, 5.39 cm, and 3.68 cm at Rongcheng, Taizhou, and Dachaidan, respectively. Therefore, the C n 2 profiles and their characteristics in these typical climate sites provide useful information to assess the effect of laser transmission in the atmosphere, which are usually used in the design of optoelectronic systems and astronomical site testing.

No abstract

By using wave optics numerical simulation, the intensity-hole effect, beam spreading and wandering properties of Gaussian vortex beam propagation in atmospheric turbulence are investigated quantitatively. It is found that an intensity hole in the center of the beam pattern appears gradually as a Gaussian vortex beam propagates. The size of the intensity hole increases with the increase of the topological charge of the vortex phase. However, the intensity hole could to some extent be filled with optical energy by atmospheric turbulence, especially in strong turbulence. The radius of the intensity hole first decreases and then increases with the growth of turbulence strength. The effective radius of vortex beam with larger topological charge is greater than with a smaller topological charge. But the topological charge has no evident influence on beam wandering.