The superposition of basic non-diffracting beams triggered new research hotspots lately, laying opportunities for long-distance wireless optical communication. The Lommel-Gaussian (LMG) beam formed by the superposition of Bessel-Gaussian light not only possesses non-diffraction feature, but also has tunable symmetry. With the help of Poynting vector analysis, we observed a smaller radial energy flow component during the propagation of the high order symmetrical LMG beam, which allows it to maintain the original beam profile over long distance. Thanks to the energy oscillation of the mainlobe and sidelobes, the mainlobe blocked by the symmetrical LMG beam can be restored. Also, the random phase screen with angular spectrum method is used to describe the beam behaviors in turbulence. The results show that the symmetry LMG is preferred in free space optical communication, and the asymmetric LMG performs poorly due to asymmetric energy transfer.

为了能更加灵活方便地实现高精度的时频信号传递, 以空间链路代替光纤进行时频传递, 阐述了自由空间光频梳频率传递基本原理, 实验通过102 m的自由空间链路, 将锁定至铷原子钟上的飞秒光频梳发送到远端, 采用高速探测器直接探测, 通过高精度频率计数器采集光频梳重复频率数据。实验结果表明: 该系统最终实现接收端100 MHz重复频率信号在30 min内抖动范围为3.5 mHz, 重复频率稳定度为4.26×10-12/s、4.81×10-13/100 s。