分析对比了星地激光通信系统中由于大气湍流和大气色散导致的脉冲展宽.计算了大气湍流导致脉冲展宽量与湍流大气折射率结构常数、传输距离、传输链路天顶角和初始脉宽之间的关系.根据大气压强和温度随高度变化的实测数据,推导出1.55μm波段的大气折射率,计算得到大气色散导致脉冲展宽量与光谱宽度、传输距离、传输链路天顶角、初始脉宽和信号光波长之间的关系.数值模拟结果表明:当输入脉宽大于0.5 ps时,大气湍流导致脉冲展宽可以忽略不计;当输入脉宽大干20 ps时,大气色散导致脉冲展宽可以忽略不计.脉冲展宽将导致系统传输带宽降低,计算了特定条件下接收端脉宽和系统最大允许的传输带宽.%The temporal broadening of optical pulses in satellite-earth laser communication systems. The expression of turbulence-induced pulse width broadening was given, in which the turbulent atmosphere index-of-refraction structure constant, propagation distance, zenith angle and original pulse width were considered. Based on the measured datum of atmospheric parameters, the refractive index in 1.55 μm was derived and the relationship of dispersion-induced pulse broadening to the spectral width, propagation distance, zenith angle, original pulse width and the wavelength of optical signal was obtained. The simulation results show that the turbulence-induced pulse broadening can be neglected for the pulse width greater than 0. 5 ps, however, the dispersion-induced pulse broadening can be neglected for the pulse width larger than 20 ps. The received pulse width and maximum achievable bandwidth are calculated in this paper under certain conditions.
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