Optical Phase-Locked Loop Technology in Inter-Satellite High-Speed Coherent Laser Communication Systems
(2.State Key Laboratory of Advanced Optical Communication Systems and Networks, Shanghai Jiao Tong University, Shanghai, China 200240)
【Abstract】A homodyne coherent laser communication system has the characteristics of high speed and long-distance transmission, and it plays an important role in the establishment of inter-satellite high-speed laser communication network. The operating principle of optical phase-locked loop is analyzed, and the corresponding mathematical model is established. The open-loop and closed-loop transfer functions of optical phase-locked loop are obtained. The error transfer function is derived. The influencing factors on loop bandwidth are analyzed. The phase noise error of phase-locked loop is analyzed, and the relationship among error factor, detection sensitivity and loop bandwidth is established. The optimized bandwidth of phase-locked loop is 1.5 MHz, and the bit error rate of the receiver is tested. The receiving sensitivity of −41.4 dBm and the bit error rate of 10−7 are obtained when the communication rate is 5 Gbit/s and the modulation mode is binary phase shift keying.
【Keywords】 optical communications; error transfer function; phase noise; receiving sensitivity;
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