无线光通信系统中部分相干阵列光束的传输特性研究

Propagation Properties of Partially Coherent Array Beams in Free Space Optics System

根据广义Huygens-Fresnel原理和修正von Karman谱模型,推导得到无线光通信系统中相互独立的部分相干高斯一谢尔模型(GSM)阵列光束在大气湍流中传输时的光强分布、均方根束宽和桶中功率解析式,并对不同因素影响下的自耦合特性、光束扩展和桶中功率进行了数值分析。结果表明,部分相干GSM阵列光束在大气传输过程中,当到达某一距离时多束光能合成一个平顶光束,再演变为高斯光束,且阵列光束在大气湍流中的自耦合特性比在自由空间中好;湍流外尺度对光强分布、光束扩展影响很小,可以忽略;部分相干GSM阵列光束与部分相干单GSM光束相比,具有更强的抑制湍流特性,有利于实现远距离通信。

Based on the generalized Huygens-Fresnel principle and the modified yon Karman spectrum model, the analytic expressions of the intensity distribution, the root mean square beam width and the power in the bucket of mutually-independent partially-coherent Gaussian-Shell model （GSM） array beams in the free space optics system are derived when the beams propagate in the atmospheric turbulence. The self-coupling characteristics, the power in the bucket and the beam spreading are analyzed numerically under the influence of different factors. The results show that when the partially coherent GSM array beams propagate for a certain distance in the atmospheric turbulence, they will be synthesized into a flat-topped beam which then evolves to a Gaussian beam. Moreover, the self-coupling characteristics of the array beams in atmospheric turbulence are better than those in free space. The influence of turbulent outer scale on the intensity distribution and beam spreading is very small, and can be ignored. Compared with the partially coherent single GSM beam, the partially coherent GSM array beams have stronger anti-turbulence properties, which is beneficial to realizing long-distance communications.