Fig. 1. Schematic of coherent detection

Fig. 2. Schematic of polarization controller PolaRITE III

Fig. 3. Optical path of mixer

Fig. 4. Experimental device for polarization control of coherent optical communication system

Fig. 5. Influence curves of p1 on the performance of the algorithm

Fig. 6. Influence curves of p2 on the performance of the algorithm

Fig. 7. Variation curves of intermediate frequency signal amplitude

Fig. 8. Changes of polarization states of signal light

Fig. 9. Variation curves of signal light Stokes parameters

Fig. 10. External filed experiment of coherent optical communication. (a) Experimental link; (b) transmitting terminal; (c) receiving terminal

Fig. 11. Changes of polarization states of signal light. (a) 2018-04-23, 21:30-22:30, sunny, 16 ℃; (b) 2018-04-25, 17:00-18:00, cloudy, 17 ℃; (c) 2018-05-06, 22:00-23:00, rain, 14 ℃

Fig. 12. Amplitude variation of intermediate frequency signal in polarization control system. (a) 2018-04-23; (b) 2018-04-24