湍流大气中高斯光束焦移的数值模拟研究

采用数值模拟方法对聚焦高斯光束在湍流大气中传输的焦移进行了研究.结果表明:湍流大气中高斯光束的焦点不再位于真空焦点位置,而是向发射点移动,且前移的幅度随湍流强度的增大而增大,这与理论预计结果一致.引用焦深概念描述光束在焦点附近的准直特性,结果显示:在弱起伏和中等强度起伏情况下,光束的焦深随着湍流强度的增大而增大,焦点附近光束准直度提高；在中等和强起伏情况下,光束在焦点附近高度准直.

Numerical Investigation into Focal Shift of Gaussian Beam Propagating in Turbulent Atmosphere

The focal shift of a focused Gaussian beam propagating in turbulent atmosphere is investigated using numerical simulation. It is found that the focus always shifts toward the transmitter, and the length of the focal shift will increase with the increasing of turbulence strength.These results are in excellent agreement with theoretical results. By using focal depth the collimated characteristic of beam near focus is described. Simulation results show that focal depth increases with turbulence strength for weak to moderate turbulence, and in cases of moderate to strong turbulence the beam is highly collimated on both sides of the beam waist.