1550nm is chosen as the work wavelength , cassegrain transmitting - receiving antenna as the optical antenna of the system through the elucidation of how to choose the work wavelength and optical antenna of comm - unication system . the structure and theoretical design parameter of apt sub - system have been presented through the discussion of the optical signal power estimation of apt sub - system , beam divergence angle , pointing error , and error signal extraction . compared with existed optical wireless communication system , the design scheme proves applicable 通过对通信系统工作波长选择、光学天线选择等阐述，选择了1550nm作为系统工作波长、卡塞格伦（ cassegrain ）收发合一天线作为系统光学天线；通过对apt子系统功率测算、束散角和瞄准误差、误差提取信号等的讨论，给出了apt子系统结构和理论设计指标，并将其与现有的光无线通信系统进行比较，说明该设计方案是可行的。
The main contents are as follows : 1 . the spectral characteristics of a multimode fiber bragg grating are theoretically and experimentally studied . on this basis , we successfully propose and demonstrate a simple switchable dual - wavelength ytterbium - doped fiber laser and an edfl operating in l - band based on a multimode fiber grating , respectively 主要内容包括: 1 .对多模光纤布拉格光栅的特性进行了理论及实验研究,并首次将多模光纤光栅应用于光纤激光器进行波长选择,得到了室温下稳定工作的可开关双波长的掺镱及掺铒光纤激光器。
