Propagation Properties Of Random Phase Array Beams In Turbulent Atmosphere

With the development of laser radar, atmospheric optical communication, laser beam propagation in turbulent atmosphere is widely concerned, and in recent years, the application of array beams made by single beam coherent combination of in turbulent atmosphere, such as remote sensing, and long distance optical communication has received much attention. At present, the theoretical research work is mostly focused on the assumption that the initial phase of each beam is the same, but in the actual work, the random phase difference between the beams directly affect the beam synthetic effect, that is, the intensity distribution of the beam and the beam quality. So, with the pursuit of high power laser is different, the different branches of the random phase modulation of the active phase modulation of the fiber array synthesis, can produce the spatial coherence of the partially coherent light, and its effective suppression of the turbulence in the atmospheric transmission characteristics.so it is of practical significance and value to study the propagation properties of random phase array beams in atmospheric turbulence.In order to overcome the shortcoming of the Kolmogorov turbulence spectrum and the Tatarskii turbulence spectrum at the origin, the influence of the turbulent atmosphere on the beam propagation is studied by using the Karman von spectrum model. In this paper, the phase fluctuation of atmospheric turbulence is simulated by using the simulation method of the multiphase screen, the far field spot of Gauss array beam are studied by numerical simulation, and the statistical analysis is carried out. The intensity distribution, the beam drift and the light intensity of the Gauss array beam in the turbulent atmosphere are studied by numerical simulation method. Results show that when array beams propagating through weak turbulent atmosphere, the central bright spot intensity is uniform, and the light spot is broken and intensity distribution is disordered when turbulence gets stronger. Beam wander centroid displacement of array beams increased as turbulent effects increased. With the increase of the transmission distance, the scintillation index increases,and then tends to saturation value when transmissions to the far field. The mathematical model and calculation result can offer a reference for practical engineering applications.This paper introduces the principle of random phase optical fiber array produce partially coherent light. A telescope is designed to expand the partially coherent light, the intensity distribution of the optical fiber array beam transmitted through the ABCD system is derived, and the ideal effect is obtained by comparing the alignment. Actual atmospheric density with height from the ground different changes, atmospheric turbulence intensity is different in the different height, air path of partially coherent light in the turbulent atmosphere transmission characteristics of need to consider the influence of the slant path of the light beam. Based on the extended Huygens-Fresnel principle, the properties of a beam array with random phase distributions propagation through a turbulence atmosphere in a slant path are analytically investigated. The beam spreading of random phase array beams is studied. Beam width in the propagation in the slant path not only with waist radius, turbulence intensity and transmission distance related, but also with the zenith angle are closely related. At last, the scintillation index of the radial distribution of random phase array beams is derived, and the influence of the radial radius and the number of beams on the axial and off-axis scintillation index is discussed.