空间光混频器分光性能的分析与优化

为了进一步提高零差相干光通信系统的接收灵敏度,对空间光混频器的信号光分光比进行了优化。根据零差相干通信系统数学模型,推导了信号光分光比和环路相位误差、通信误码率的数学表达式,经过计算分析可知当光混频器Q支路的信号光满足锁相环要求时,可通过提高I支路信号光分光比来降低误码率和提高接收灵敏度。在分光比优化后光混频效率提高了53.5%,通信探测灵敏度提高了3dB。利用VPI软件进行建模仿真,得到不同分光比下系统的眼图和相位噪声功率。仿真结果显示,探测灵敏度提高了2.83dB。最后,搭建了零差相干光通信桌面实验系统,研究了空间光混频器分光比和系统误码率、锁相环工作的影响规律,当分光比由0.5减小至0.2时,系统误码率由3.53×10~(-9)下降至4.25×10~(-10),当分光比为0.1时,锁相环失锁,误码率为1。实验结果基本符合理论和仿真结果,所得分光比的影响规律和优化结果将为空间零差相干通信系统的研制提供技术参考。

Analysis and optimization of splitting performance for space optical hybrid

Signal light splitting ratio of space optical hybrid was optimized in order to further improve received sensitivities of homodyne coherent optical communication systems.According to the mathematical model of homodyne coherent communication systems,mathematical expression of signal light splitting ratio,loop phase error and bit error rate (BER) was deduced.Through calculation and analysis,it indicated that when signal light of Q branch for optical hybrid met the requirement of phase-locked loop,Bit Error Rate (BER) could be reduced and received sensitivity could be improved by improving the signal light splitting ratio of Ⅰ branch.The optical coherent efficiency increased by 53.5 ％ and the communication detection sensitivity increased by 3 dB after optimization of the splitting ratio.Eye diagrams and power of phase noise of the system at different splitting ratios were obtained by modeling and simulation with VPI software.The simulation results show that the detection sensitivity is improved by 2.83 dB.Finally,a table experiment system of homodyne coherent optical communication was built to study influence rules of splitting ratio of space optical hybrid,system error rate and phase-locked loop.When splitting ratio decreases from 0.5 to 0.2,system error rate declines from 3.53× 10-9 to 4.25× 10-10.When splitting ratio is 0.1,phase-locked loop loses efficacy and the bit error rate is 1.The experiment results conform to the theory and simulation results basically,and the influence rules and optimization results of splitting ratio will provide technical references for development of space homodyne coherent communication systems.