Experiment and analysis of the effect of fine tracking system on the unstable platform in laser communication

Atmospheric turbulence and platform vibration in the space optical communication can cause the offset and jitter of beam, which further result in the fluctuations of received optical power. To resist this effect, a communication system with fine tracking systems in the receiver and transmitter is designed. The system is used in the experiment of laser communication between high-rise buildings over a distance of 3.5 km. After adding a vibration source to the transmitter, the centroids of spots captured by the camera of the transmitter and the optical power of receiver are recorded for the purpose of analysis. When the vibration source works at the designated frequency, a peak appears at the corresponding frequency in the spectrum of the spot centroids and the optical power of receiver. Then the peak disappears once the fine tracking system begins to work. Compared with the condition without the fine tracking system, the minimum value of the optical power of receiver is increased by 5 dB, and the standard deviation is decreased by 30%.