Numerical Simulation Of Laser Propagation In Atmospheric Turbulence And Its Impact Analysis

As the rapid development of the laser technique, the laser is widely applied in the near earth space, but these engineering are affected by the atmospheric turbulence. The optical scintillation, spot dancing, beam expansion and angle fluctuation caused by the atmospheric turbulence restrict the application of the laser in the near earth space. The existing theory is only suitable for analyzing the weak atmospheric turbulence. In order to study the application of laser in the near earth space we must analyze the moderate and strong atmospheric turbulence and research the way to solve those problems. Based on such idea, the research was made as follows:1. The fundamental roles of atmospheric turbulence and its impact for optical transmission were introduced, the formula for calculating the optical scintillation,spot dancing,beam expansion and angle fluctuation was analyzed. The analytic theory of optical scintillation can be applied to analysis the moderate and strong atmospheric turbulence. This theory will be helpful for application of laser in the atmosphere.2. A transmission process of the laser propagation through atmospheric turbulence was simulated under the Matlab software environment with the phase-screen method. The method of phase-screen is a hotspot for researching atmosphere, it is more effective for strong turbulence. The power spectrum method based on fast Fourier transform (FFT) to simulate phase screens disturbed by atmospheric turbulence is very simple and the calculating speed is very fast. Because the laser used in the atmosphere generally is Gaussian-beam, so we numerical simulate the Gaussian-beam transmitting in the atmospheric turbulence, it makes our numerical simulation process was close to the facts and the various statistical results are also more useful for the practical reference. By the analysis of a large number of numerical simulation results, it can be seed that the simulation results are corresponded with the phenomenon and result of experimental observations, at the same time, we conducted the experiment about the laser transmit in the atmospheric turbulence to check up our simulations.3. With the requirements of practical application, the multi-beam transmission was proposed to overcome the effect of atmospheric turbulence, the principle and the results of this method were analyzed. Multi-beam laser transmission is a very important method in recent years, its design is simple and practical effect is very good. After the theoretical analysis and numerical simulation of this paper, the theoretical basis of multi-beam transmission to reduce the light intensity fluctuation and the spot dancing that caused by atmospheric turbulence was provided, also this article provided certain reference value for the practical application of the multi-beam method to overcome the effect of atmospheric turbulence.